Britain says it foils "mass murder" plane bomb plot

LONDON (Reuters) - British police arrested 24 people in overnight raids and said on Thursday they had foiled a plot to commit "mass murder" by blowing up several aircraft flying over the Atlantic Ocean to the United States.

Tough new security measures brought chaos to airports on both sides of the Atlantic in what U.S. President George W. Bush described as a stark reminder his country was at "war with Islamic fascists".

Pakistan said it intelligence agencies helped thwart the plot and had arrested an unspecified number of people.

"We are confident we have disrupted a plan by terrorists to cause untold death and destruction," said London police's Deputy Commissioner Paul Stephenson. "Put simply, this was intended to be mass murder on an unimaginable scale."

A U.S. Homeland Security department official said all the people arrested in Britain were British citizens. Overnight raids were carried out in the capital London, southeast England and Britain's second city, Birmingham.

The suspected plot raised the spectre of a strike to rival the scope of the Sept. 11, 2001, attacks on the United States ahead of their fifth anniversary, and came 13 months after four British suicide bombers killed 52 commuters on London transport.

U.S. officials said they saw signs of al Qaeda's methods, but it was too early to draw conclusions on whether the global militant group was involved.

British Interior Minister John Reid said police were confident the main players had been detained.

LIQUIDS BANNED

U.S. Homeland Security Secretary Michael Chertoff said the plot was in the final stages of planning before execution.

"The terrorists planned to carry the components of the bombs, including liquid explosive ingredients and detonating devices, disguised as beverages, electronic devices or other common objects," he said.

Departure halls were jammed with people, waiting as airlines cancelled flights and trying to sort out their bags as hand luggage and liquids were banned from flights and passengers with babies were made to publicly taste their food.

"It's tough. We have nine pieces of luggage and we are going to have to bring it all to the hotel and back," said Michael Suncin, who was en route to Sweden and standing in a long queue for hotel reservations at London's main Heathrow airport.

In the United States, authorities banned liquids and gels from flights. In Britain, all hand luggage was banned, and passengers were allowed on board only with a single clear plastic bag of items on an official list.

British security sources said they had been watching the suspects for eight months. They did not rule out an al Qaeda link, but played down direct involvement by the militant group.

Stephenson said the plot had "global dimensions" and that police were cooperating with foreign agencies.

The U.S. television network ABC news quoted unnamed American officials saying five suspects were still on the loose and being eagerly hunted. British police declined to comment.

U.S. CARRIERS

Chertoff said U.S. carriers were targeted. A U.S. official speaking on condition of anonymity said Continental Airlines, United Airlines and American Airlines flights were the focus.

The United States raised the threat level for British-U.S. passenger flights to "red", its top level, for the first time.

Britain's security services upped the threat level in the country to "critical" from "severe", the highest of its five ratings, which means "an attack is expected imminently".

Shares in European airlines fell. British Airways dropped more than 5 percent. The pound fell against the dollar and the euro. Oil fell to below $76 a barrel on fears the security threat might slow growth worldwide and cut oil demand.

Tony Blair's office said the prime minister, on holiday in the Caribbean, had briefed U.S. President George W. Bush.

Last month, al Qaeda called on Muslims to fight those who backed Israel's attacks on Lebanon and warned of attacks unless U.S. and British forces pulled out of Iraq and Afghanistan.

Al Qaeda hijacked passenger aircraft in September 2001 to destroy the World Trade Center in New York. Briton Richard Reid was arrested in December 2001 for trying to blow up a plane headed to the United States using a bomb in his shoe.

The British Airports Authority asked all European carriers to suspend flights to Heathrow. British Airways cancelled short-haul flights to and from the airport, which processes 180,000 passengers a day in the peak summer period.

(Additional reporting by Katherine Baldwin, Adrian Croft, Peter Griffiths, Catherine Hornby, Gideon Long, Jeremy Lovell, Jason Neely, Michael Smith in London, Todd Eastham and Deborah Charles in Washington and Jon Boyle in Paris)

By Michael Holden and David Clarke