Abdulla Ahmed Ali, the 28-year-old ringleader of the group, was given a minimum of 40 years before he would be eligible for parole. His accomplices, Assad Sawar, 29, and Tanvir Hussain, 28, received minimum sentences of 36 and 32 years, respectively.

Addressing Ali during sentencing, Judge Richard Henriques said, "I have concluded you are a driven and determined extremist with boundless energy and an ambition to lead a terrorist outrage of boundless proportion. By this conspiracy you sought the attention of the world, and you now have it."

The thwarted suicide attack, intercepted by British intelligence services in August 2006, would have been the "worst atrocity since 9/11 and woiuld have inflicted heavy casualties in the name of Islam," the court in London heard last week.

All three men, though born in Britain, had close links with Pakistan. Four other men were found not guilty of involvement in the plot.

Henriques said the defendants had "embraced Islamic extremism and it is that burning extremism that has motivated you throughout this conspiracy and is likely to drive you again."

Trial almost didn't happen

At a trial a year ago, Ali, Hussain and Sarwar were found guilty of conspiracy to murder involving liquid bombs - but that jury could not decide whether their plans extended to detonating the devices on planes.

An appeal by Britain's Crown Prosecution Service (CPS) led to a retrial, with the jury concluding that such a terror plot did exist, ultimately leading to last Monday's convictions at Woolwich Crown Court in London.

During the trial, the court was told that Ali picked out seven flights to San Francisco, Toronto, Montreal, Washington, New York and Chicago that departed from London's Heathrow Airport within a two-and-a-half hour period. Jets were operated by United Airlines, American Airlines and Air Canada.

The prosecution alleged that the attack would have caused "mass murder on an unimaginable scale" and would have "exceeded the carnage" of the September 11 attacks in the US in 2001.

Plan foiled thanks to British surveillance

Reports said the security services, courts and police had spent a total of 35 million pounds (39 million euros, $57 million) on foiling the plot and bringing the men to justice.

Undercover surveillance officers had watched Ali converting a flat in east London into a bomb factory, which was also used to record suicide videos in which the British public was warned to expect "floods of martyr operations."

According to prosecutors at the trial last week, the three men plotted to drill holes in the bottom of plastic drinks bottles, drain the contents and inject liquid explosive with a syringe before sealing the holes with glue. That way the bottle tops would remain unopened.

The home-made liquid explosive was to be concocted from hydrogen peroxide and Tang, a soft drink available in powdered form. When mixed with such an organic material at an appropriate strength, hydrogen peroxide has explosive qualities.

The bottles would be detonated using the substance HTMD, concealed in regular AA 1.5-volt batteries. The detonator would have been ignited using a metal wire or a small light bulb, the court heard.

The plan to blow up the seven airliners crossing the Atlantic to Canada and the US led to a worldwide ban on carrying liquids in hand luggage.

mrm/dpa/AFP/Reuters
Editor: Susan Houlton