The computer models that guided decisions to impose a no-fly zone across most of Europe in recent days are based on incomplete science and limited data, according to European officials. As a result, they may have over-stated the risks to the public, needlessly grounding flights and damaging businesses. "It is a black box in certain areas," Matthias Ruete, the EU's director-general for mobility and transport, said on Monday, noting that many of the assumptions in the computer models were not backed by scientific evidence.

European authorities were not sure about scientific questions, such as what concentration of ash was hazardous for jet engines, or at what rate ash fell from the sky, Mr Ruete said. "It's one of the elements where, as far as I know, we're not quite clear about it," he admitted. He also noted that early results of the 40-odd test flights conducted over the weekend by European airlines, such as KLM and Air France, suggested that the risk was less than the computer models had indicated.

The acknowledgement that the computer models were flawed is likely to provide ammunition for critics who believe that authorities have shown excessive caution. The closure of much of the airspace over Europe over the past five days is estimated to have cost airlines a total of $200 million a day in lost revenue.

Britain's Met Office, the national weather service, said the vast cloud that has grounded thousands of flights across northern Europe reached Newfoundland on Monday. However, the winds that pushed the ash to the edge of North America are expected to change direction in the next couple of days, preventing the cloud from covering more of Canada and the United States.

Airlines have suffered losses described as being worse than after the 9/11 attacks after aviation officials closed parts of Europe's airspace on fears the ash could paralyze jet engines. "It is just skirting into the Newfoundland area over the next 12 to 18 hours," Bob Syvret, duty forecaster at the Met Office, told Reuters. "It doesn't look as if it is going to get much further west than that, just on the coast and a little further inland."

It showed the cloud jutting south from the volcano in Iceland, covering much of northern Europe and then spreading west over the Atlantic and east over Russia. Estimating the density of the cloud at its extremities is difficult and warnings for aviation in North America would be a matter for US and Canadian officials, Syvret added.

Last week, two Finnish Air Force F-18 fighter-bombers suffered similar damage while flying through the ash plume that has paralyzed air traffic over much of Europe. Both landed safely, but their jet engines will require expensive overhauls. Volcanic ash tends to stick to a jet engine's interior parts, such as the turbines, where it melts to form a glassy coating. This restricts air flow and heats up the engine, leading to engine failure.

Scottish airports are still expected to reopen from 0700 BST, but Nats said it would report again at 0300. A further update will be made at 0900 BST on Tuesday. Nats said more airspace over England was expected to become available from 1300 BST although not as far south as London's main airports.

In a statement, Nats said: "The volcano eruption in Iceland has strengthened and a new ash cloud is spreading south and east towards the UK. This demonstrates the dynamic and rapidly changing conditions in which we are working." It said it expected the situation to change overnight, and pointed out it was working closely with the Met Office and the UK's safety regulator, the Civil Aviation Authority.

Roads and communications are sparse in the area, and casualty reports take time to reach authorities. The quake was felt in Kabul as well as the neighboring countries of Uzbekistan and Tajikistan. Baghlani said three districts of scattered mud-walled villages were affected, with more than 300 homes damaged and dozens of head of livestock killed. Landslides sparked by the quake had blocked roads, making even more arduous what was already an eight-hour drive along winding mountain trails from the provincial capital of Aybak.

The Hindu Kush region is capable of producing large earthquakes along faultlines where India slammed against the Asian continent millions of years ago. In 1998, a pair of quakes measuring 5.9 and 6.6 struck along Afghanistan's border with Tajikistan, killing more than 6,000 people. A 5.3 quake that hit Baghlan province next to Samangan in 2002 killed about 1,000 people.

Airports and airlines are questioning the need for curbs said to be costing airlines $200 million (130 million pounds) a day. The International Air Transport Association (IATA) has criticised European governments' response. "We must move away from this blanket closure and find ways to flexibly open air space, step by step," IATA head Giovanni Bisignani told a news briefing in Paris.

The enormous shroud of fine mineral dust particles now stretches from the Arctic Circle in the north to the French Mediterranean coast in the south, and from Spain into Russia. Airspace remains closed, or partially closed, in more than 20 countries. Sixty-three thousand flights have been cancelled in the four days since the clampdown began. And the prospect of a return to normal air travel remains far from clear.

In another development, hundreds of thousands of Kenyans working in agriculture, the country's largest export sector, face economic uncertainty because of the flight bans. Refrigerated stores at Nairobi airport and on farms are now completely full, and a huge amount of fresh flowers and vegetables destined for the European market is in danger of perishing, the BBC's East Africa correspondent, Will Ross, reports

The ships HMS Ark Royal, HMS Ocean and HMS Albion have been pressed into action and are heading for Spain and unspecified Channel ports. Flight restrictions were extended to at least 0100 BST Tuesday. Travel agents' association Abta said its "rough estimate" was that 150,000 Britons are currently stranded abroad. HMS Albion was deployed to Spain to return members of the 3 Rifles regiment to the UK, as they remain stranded on their way back from Afghanistan. Gordon Brown has spoken to the Spanish premier about the feasibility of some Britons being flown into Spain before a journey by sea to the UK.

Arriving for the Cobra meeting, the Cabinet Office Minister Tessa Jowell said the government will "take advice from [national air traffic control service] Nats and no-one else". She also confirmed that Transport Secretary Lord Adonis is in hourly contact with individual airlines and denied the government had been slow to act over the crisis. "At every airport where there are likely to be UK citizens trying to return home there have been consular staff," she said.

Cabinet ministers met to discuss plans to deal with the situation on Sunday, with Business Secretary Lord Mandelson saying afterwards: "We will mobilise all possible means to get people home." Security minister Lord West, a former head of the Royal Navy, said: "We clearly have a reasonable lift capacity within the Royal Navy for lifting people... we are finding exactly what ships are available, what would be able to move, what's the best port to go to." Other ideas included requisitioning merchant ships, he said.

Dr Guy Gratton, head of the Facility of Airborne Atmospheric Measurement, a joint body belonging to the Met Office and the Natural Environment Research Council, said the test had discovered "a very complex set of ash plumes" with "six distinct layers". "Those layers are around four or five times more dense than we saw on our last flight on Friday, so it's still quite a complex mixture of clear air and very worrying, but invisible volcanic ash at all sorts of heights," he said. Our correspondent said this showed the issue was not whether the cloud was real and dangerous, but whether its extent could be accurately mapped.

The two-term Democratic president insisted he wasn't trying to restrict free speech, but in remarks Friday he said incendiary language can be taken the wrong way by some Americans. He drew parallels to words demonizing the government before Oklahoma City. On April 19, 1995, an anti-government conspiracy led by Army veteran Timothy McVeigh exploded a truck bomb outside the Alfred P Murrah Federal Building, killing 168 people.

"What we learned from Oklahoma City is not that we should gag each other or that we should reduce our passion for the positions we hold - but that the words we use really do matter, because there's this vast echo chamber, and they go across space and they fall on the serious and the delirious alike. They fall on the connected and the unhinged alike," he said.

"One of the things that the conservatives have always brought to the table in America is a reminder that no law can replace personal responsibility. And the more power you have and the more influence you have, the more responsibility you have." Clinton made the remarks at events sponsored by the Center for American Progress Action Fund on the upcoming anniversary of the bombing. He mentioned the rancorous fight over President Barack Obama's health care overhaul. Passage of the law elicited threats against some lawmakers.

"I'm glad they're fighting over health care and everything else. Let them have at it. But I think that all you have to do is read the paper every day to see how many people there are who are deeply, deeply troubled," he said. He also alluded to the anti-government tea party movement, which held protests in several states Thursday. At the Washington rally, Republican Representative Michele Bachmann of Minnesota railed against "gangster government."

Clinton argued that the Boston Tea Party was in response to taxation without representation. The current protesters, he said, are challenging taxation by elected officials, and the demonstrators have the power to vote them out of office. "By all means keep fighting, by all means, keep arguing," he said. "But remember, words have consequences as much as actions do, and what we advocate, commensurate with our position and responsibility, we have to take responsibility for. We owe that to Oklahoma City."

"The jet stream winds, which extend from 10,000 feet up to 40,000 feet, show no signs of change through Wednesday," Accuweather said in a statement. "Any ash plume that is released from the Eyjafjall volcano in Iceland will continue to threaten northern Europe and the British isles." No flights will operate out of the UK until at least 1 pm London time tomorrow, the National Air Traffic Service said today via email. German airports will remain closed until 2 pm Berlin time, the DFS air traffic control agency said. The European Organisation for the Safety of Air Navigation, or Eurocontrol, expects about 5,000 flights across Europe today, compared with 22,000 on a "normal" Saturday, it said today in a statement.

"Expect ongoing interruptions for the next four or five days," Teitur Atlason, at the Icelandic meteorological office, said in a telephone interview today. "The eruption is still in full swing, and the volcano is spewing pretty dark ashes as high into the air as 5 to 6 kilometers."

Volcanic eruptions may continue for months, curtailing European air traffic when the ash reaches the region, said Sigrun Hreinsdottir, a geophysicist at the University of Iceland in Reykjavik. "From what we've seen, it could erupt, pause for a few weeks, and then possibly erupt again."

The last eruption of Eyjafjallajokull in December 1821 continued until January 1823. The current blast has sent ash to as high as 7 kilometers (4.5 miles), according to Gudrun Larsen, a vulcanologist at the University of Iceland. The magma had to pierce 200 meters of ice before erupting, she said.

Athens was yesterday edging closer to activating a bailout from fellow European Union countries and the International Monetary Fund, which is due to send teams to the country on Monday. But Joachim Fels, co-chief global economist at investment bank Morgan Stanley in London, warned the Greek rescue proposal sets a 'bad precedent' for eurozone member states and makes it more likely that the euro area 'degenerates into a zone of fiscal profligacy, currency weakness and higher inflationary pressures'.

Mr Fels suggested Berlin may be 'better off with a harder but smaller currency union'. He added that 'recent developments significantly raise the long-term risk of a euro break-up' and that a 'scenario where a country or a group of countries want to leave to introduce a stronger currency is more likely than a scenario where a country, like Greece, wants to leave to devalue'.

Though Germany has not officially considered the proposal, Mr Fels' comments reflect the radical options being considered by EU member states as the situation in Greece worsens.

"The government is downplaying the number," said Ge Laidanzeng, a 20- year-old monk. He said that when all the bodies were retrieved from the wreckage of the town there would "definitely be more than 10,000 dead". Meanwhile, the first teams of rescue workers equipped with sniffer dogs and heartbeat detectors arrived in Jiegu, hampered by the 12-hour journey from the nearest major airport in Xining. As they clambered over the rubble, however, it was soon clear that hopes of any further survivors were fading fast.

Relief supplies continued to trickle into Jiegu, but with the entire town's population of 100,000 sleeping in the open, the supplies of tents, blankets and food were quickly snapped up, leaving thousands of people still in need.

It alleges that the bank marketed complex subprime mortgage packages but did not reveal that a major hedge fund had bet against the securities. Goldman's shares fell 7.4% on the news of the accusations against the firm and one of its Vice Presidents. The bank escaped relatively unscathed from the financial crisis.

Airports across Britian were deserted today after an unprecedented lockdown of airspace prompted by the threat from a deadly cloud of volcanic ash. The National Air Traffic Service (NATs) has now grounded flights in and out of the UK until at least 1am tomorrow. But with the source of the ash - a volcano 700 miles away in Iceland - still spewing smoke into the atmosphere, there are already fears the chaos could go on for days if not weeks.

Some experts said there could be disruption for six months as a result of contaminated air drifting over northern Europe. NATs will review the situation at 1pm today and put out a statement about services tomorrow at 2.30pm. No jet planes can fly except in an emergency because the dust causes their engines to fail. Health officials have told those with conditions such as asthma to stay indoors.

The cancellations have already caused the greatest mayhem to air travel since the Second World War. This morning there were few passengers at UK airports - which usually cater for 500,000 people a day - with most chosing to stay home. The Health Protection Agency said the ash will cause itchy eyes, a runny nose, sore throat or dry mouth when the particles land.

Those with bronchitis, emphysema and asthma were advised to stay inside because the ash could seriously inflame their conditions. The ash, which will drift down from the north of the country, was predicted to appear as a dusty haze and may smell of sulphur or rotten eggs, or strongly acidic.

The volcanic eruption in Iceland, which began on Wednesday, is just such a reminder. As ash spews out across northern Europe, grounding all flights across Scandinavia and the UK, we begin to realise how powerless we humans are. But as volcanic eruptions go, the current fireworks on Iceland are small fry.

Scientists rank volcanoes according to how explosive they are, using the volcanic explosivity index (VEI), which goes from zero to eight. The measurement is based on how much material is thrown out of the volcano, how high the eruption goes and how long it lasts. Like the scale used to measure earthquake size, the VEI is logarithmic - meaning that a volcano with a VEI of five is 10 times more powerful than one with a VEI of four.

To volcanologists, Iceland is heaven. There are 30 active volcanic systems on the island and very frequent firework displays. Geologists believe that the reason for Iceland's explosive nature is because it sits over a "mantle plume" - a rising column of abnormally hot molten rock, originating at the edge of the Earth's core.

To make matters even more spectacular, this particular mantle plume has positioned itself under the mid-Atlantic ridge: the crack that runs down the middle of the Atlantic, where the ocean floor divides and continuously spews out fresh lava.

The US, however, is not happy with the Syrian transfer of missiles to Lebanon - and an expert says Israel will have to take action.

Profssor Eyal Zisser, head of the Dayan Center for Middle Eastern Studies in Tel Aviv University, told Arutz-7 that the news requires Israel to make some difficult decisions. "There's no question that the transfer of [these missiles] is an escalation," Zisser said. "These Scuds are more precise than those that Saddam Hussein launched at us in the Gulf War of 1991, and they have a longer range as well."

White House spokesman Robert Gibbs said the US has relayed its concern to the Syrian government, Senator John McCain raised the issue at the hearing on Iran on Wednesday, and Under Secretary of Defense Flournoy said the US is "very concerned" by these reports.