Three British Muslims were found guilty today of conspiracy to murder thousands of passengers and crew in an unprecedented airline bomb plot that could have proved as deadly as the 9/11 attacks.

After a retrial at Woolwich Crown Court, jurors found the ringleader, Abdulla Ahmed, and two other men, Assad Sarwar and Tanvir Hussain, guilty of plotting to use liquid bombs to blow up airliners en route from Heathrow to the United States.

Another defendant, Umar Islam, was found guilty of a more general charge of conspiracy to murder because jurors could not decide whether he knew of the specific targets in the plot three years ago.

Three other men, Arafat Khan, Ibrahim Savant and Waheed Zaman, were found not guilty of conspiracy to blow up aircraft but could face a retrial on the more general conspiracy to murder charge because jurors could not reach a verdict.

The eighth defendant, Muslim convert Donald Stewart-Whyte, was found not guilty on the terrorism charges but had pleaded guilty to a firearms offence.

Ali, 28, was the leader of an East London terror cell inspired from Pakistan, the court heard. He had planned to detonate home-made liquid bombs in suicide attacks on transatlantic aircraft bound for major north American cities.

It was the most complex and daring British-based terrorist conspiracy in modern times and, according to the Crown Prosecution Service, could have killed "hundreds of innocent people".

Prosecutors said that the plot was largely run from Pakistan and produced e-mails which mention a figure referred to as "Paps" or "Papa", believed to be a pen-name used by a British-born Muslim, thought to have been a key facilitator of al-Qaeda activity in Britain.

Counter-terrorist police, the security services and prosecutors spent more than £35 million foiling the plot and bringing Ali to justice.

The arrest of the gang in August 2006 sparked tight restrictions on carrying liquids on to aircraft that led to travel chaos and which remain largely in place three years later, although detectives complained that their operation had been compromised by the fact that news of the plot had leaked out from Washington first.

The guilty verdict will come as an enormous relief for ministers who endured heavy criticism for introducing the draconian luggage restrictions.

It was also seen as a vindication of the decision to retry Ali and his fellow plotters after he was found guilty of conspiracy to cause explosions last September. The previous jury at the South London court failed to reach verdicts on the specific airline plot.

Alan Johnson, the Home Secretary, said: “I am pleased that the jury has recognised that there was a plot to bomb transatlantic flights and that three people have been convicted of that plot.

“This case reaffirms that we face a real and serious threat from terrorism. This was a particularly complex and daring plot which would have led to a terrible attack resulting in major loss of life.

“This was the largest ever counter terrorism operation in the UK and I cannot thank enough those involved for their professionalism and dedication in thwarting this attack and saving thousands of lives.”

British-born Ali, of Walthamstow, was inspired by the July 7 bombers and Osama bin Laden and considered taking his baby son on his suicide mission.

He planned to smuggle home-made bombs disguised as soft drinks on to passenger jets run by United Airlines, American Airlines and Air Canada.

The hydrogen peroxide devices would have been assembled and detonated in mid-air by a team of suicide bombers.

Ali singled out seven flights to San Francisco, Toronto, Montreal, Washington, New York and Chicago that departed within two-and-a-half hours of each other.

Authorities on both sides of the Atlantic would have been left powerless to stop the destruction once the first bomb exploded.

Police said the plot was drawn up in Pakistan with detailed instructions passed to Ali during frequent trips to its lawless border with Afghanistan.

They believe a mystery al-Qaeda bombmaker was responsible for the ingenious liquid bomb design, concealed within 500ml Oasis or Lucozade bottles.

Surveillance teams watched Ali on his return to Britain as he assembled his terror cell, gathered materials and identified targets.

Undercover officers looked on as the unemployed former shop worker used cash to purchase a £138,000 second-floor flat in Forest Road, Walthamstow.

They planted a secret bug that revealed it was converted into a bomb factory where Ali met others to construct the bombs.

The flat was also used as a location for Ali and others to record suicide videos threatening further attacks against the West.

In his video Ali warned the British public to expect "floods of martyr operations" that would leave body parts scattered in the streets.

Ali was watched as he used public phone boxes, mobile phones and anonymous e-mail accounts to keep in touch with mystery terrorist controllers in Pakistan.

On his arrest, he was found to be carrying an elaborate and damning blueprint for the plot scrawled in a battered pocket diary. Airport security arrangements and details of flights, including the seven highlighted services, were discovered on a computer memory stick in another pocket.

All the defendants except Mr Stewart-Whyte, a Muslim convert, admitted conspiracy to cause a public nuisance and will be sentenced next Monday.

The jury took a total of 54 hours and 11 minutes to reach their verdicts in the retrial.

Ali, wearing a dark blue sweater, showed no emotion as the verdicts were read out, while Hussain nodded his head as the verdicts were read and shrugged his shoulders as he left the secure dock at the back of the court.

Mr Stewart-Whyte looked to the ground as he was cleared before smiling. Afterwards, his lawyer demanded an independent investigation into try him on the basis on "spurious" evidence.

Bernie Duke, one of his solicitors, said: “Mr Stewart-Whyte should never have been charged. We invite the CPS to conduct an independent review into why he was tried when there was in reality only spurious evidence of his guilt and strong evidence of his innocence.”

Judge Mr Justice Henriques thanked the jury for their service over the last six months of the trial and encouraged them to attend the sentencing hearing on Monday.

Speaking after the verdicts, Sue Hemming, Head of the Crown Prosecution Service Counter Terrorism Division, said that the plot would have killed hundreds of people.

“This was a calculated and sophisticated plot to create a terrorist event of global proportions,” she said. “These men wanted to bring down several aircraft in a short space of time, indiscriminately killing hundreds of innocent people - perhaps more - if they'd succeeded in activating their devices while over cities."

Charges in full

Abdulla Ahmed Ali, Assad Sarwar and Tanvir Hussain

Guilty of conspiracy to cause explosions on aircraft, conspiracy to murder, conspiracy to cause explosions and conspiracy to cause public nuisance.

Umar Islam

Guilty of conspiracy to murder; conspiracy to cause a public nuisance. Jury failed to reach a verdict on conspiracy to cause explosions on aircraft.

Ibrahim Savant, Arafat Khan, Waheed Zaman

Guilty of conspiracy to cause a public nuisance. Not Guilty of conspiracy to cause explosions on aircraft. Jury failed to reach verdicts on conspiracy to murder.

Donald Stewart-Whyte

Not guilty of conspiracy to cause explosions on aircraft and conspiracy to murder. Admitted firearms and cannabis possession charge..

Copyright 2009 Times Newspapers Ltd.