Britain says it foils "mass murder" plane bomb plot

LONDON, Aug 10 (Reuters) British police today foiled a suspected plot to blow up several aircraft mid-flight between Britain and the United States in what Washington said might have been an attempted al Qaeda strike.

''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.'' Britain and the United States both stepped up security, causing severe delays at airports following the announcement of the reported plot, which a police source said was believed to involve a ''liquid chemical'' device.

Twenty-one people were being held after swoops in the capital London, southeast England and Britain's second biggest city, Birmingham.

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.

The suspected plot raised the spectre of another attack to rival the scope of the September 11 attacks on the United States.

US Homeland Security Secretary Michael Chertoff said that, while the operation was centred on Britain, it was international in scope and sophisticated, and involved many people.

''This operation is in some respects suggestive of an al Qaeda plot, but because the investigation is still under way, we cannot yet form a definitive conclusion,'' he said.

British police sources did not rule out an al Qaeda link, but played down direct involvement by the global militant group. Police sources said some of those arrested were British Muslims.

The security alert comes 13 months after four British Islamist suicide bombers killed 52 people and injured about 700 on London's transport network.

Interior Minister John Reid said police were confident the main players had been detained in raids overnight.

RED ALERT Shares in European airlines fell, with British Airways shares down more than five per cent. The pound fell against the dollar and the euro. Oil prices fell to below 76 dollars a barrel on fears the security threat might hurt consumer confidence, slowing growth worldwide and reducing demand for oil.

Britain has been criticised by Islamist militants for its military campaigns in Iraq and Afghanistan.

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