LONDON — Three British Muslims were convicted Monday of plotting to murder thousands by downing at least seven trans-Atlantic airliners in simultaneous attacks designed by al-Qaida to be the deadliest terrorist strike since Sept. 11, 2001.
Abdulla Ahmed Ali, 28, Assad Sarwar, 29, and Tanvir Hussain, 28, were found guilty at Woolwich Crown Court in London of leading a plan to detonate bombs on aircraft bound for the United States and Canada, using liquid explosives hidden in soda bottles.
Four other men were acquitted of conspiring to bomb airliners, but they admitted to lesser charges — in one case conspiracy to murder. An eighth man was cleared completely.
The case brought sweeping new restrictions for air passengers, including limits on the amount of liquids and gels they can take carry on board.
British and U.S. security officials said the plan was directly linked to al-Qaida and guided by senior Islamic militants in Pakistan.
Authorities estimate that, if successful, about 2,000 passengers would have died. Had the bombs been detonated over U.S. and Canadian cities, hundreds more would have been killed on the ground. Britain's Home Secretary Alan Johnson said the plot would have brought "murder and mayhem on an unimaginable scale."
Other officials said the political repercussions would have been immense, probably destroying relations between London and Washington. The case might spur new concerns over the U.S. visa waiver program, which allows citizens of many European Union countries — including Britain— to fly to the United States without visas.
Police said they think the plotters were just days away from mounting their attacks when officers rounded up 25 people in 2006. During the arrests, hundreds of jetliners were grounded across Europe.
Prosecutors said the suspects had targeted seven flights — one each from London's Heathrow airport to New York, Washington, San Francisco, Toronto and Montreal, and two to Chicago.
A test run was planned for the weekend of Aug. 12, 2006, when one plotter planned to smuggle a liquid bomb kit onto an airliner, said a senior police official, who demanded anonymity to discuss details not presented to the court. He said the attacks were likely to have been the week of Aug. 14, 2006.
Former U.S. Deputy Secretary of State John Negroponte told the Senate in 2007 that the plot "would have been on a par, or something similar to 9/11."
The plotters planned to assemble bombs in airplane toilets using hydrogen peroxide-based explosives injected into soda bottles, prosecutors said.
Britain's MI5 spy agency thinks the group planned to strike as many as 18 jetliners in two waves of bombings, and to provoke further panic with attacks on U.K. power stations. Police say some would-be second-wave suicide bombers have probably evaded arrest.
Investigations into the secondary plots — and hopes of gathering evidence to link the cell to specific terrorists in Pakistan — were curtailed as U.S. officials became increasingly nervous and ordered the arrest of one of the group's key accomplices in Pakistan.
Rashid Rauf, a British-born baker's son, is said by intelligence officials to have been the key link between the U.K. and militants in Pakistan. Rauf was arrested in the central Pakistani city of Bahawalpur in early August 2006.
Peter Clarke, head of British counterterrorism policing at the time, said Rauf's arrest was a surprise to London. Worried that the plotters would rush forward their plans, police rounded up dozens of suspects in hasty dawn raids on Aug. 10, 2006.
Former U.S. Homeland Security Secretary Michael Chertoff has denied that there was a rift with London, but other U.S. officials acknowledged that the White House was jittery.
"Given what happened on 9/11, and that this airliner plot was headed in our direction, it shouldn't come as a surprise that some here advocated taking action sooner rather than later," said a U.S. counterterrorism official, who spoke on condition of anonymity because of the sensitivity of the case.
Rauf escaped from custody in December 2007. He was the target of a U.S. drone strike in November 2008, but U.S. and British intelligence officials say they are unsure whether he is dead or alive.
Jurors found Umar Islam, 31, guilty of conspiracy to murder but could not decide if he was involved in targeting aircraft. They found three other men — Ibrahim Savant, 28, Arafat Waheed Khan, 28, and Waheed Zaman, 25 — not guilty of planning to blow up airliners but could not reach verdicts on whether they were guilty of conspiracy to murder.
All four had pleaded guilty to a lesser charge of conspiracy to cause a public nuisance. An eighth man — Donald Stewart-Whyte, 23 — was cleared of all charges. His lawyers have called for a government apology.
Judge Richard Henriques said he would sentence the men on Sept. 14.