Three Britons were found guilty on Monday of conspiracy to kill using homemade liquid bombs, but a jury failed to agree that they intended to blow up transatlantic airliners in an al Qaeda-style attack.
The verdicts came after a high-profile, five-month trial in which prosecutors had argued that eight co-conspirators planned to smuggle explosives onto half a dozen aircraft at London's Heathrow airport and blow them up midway to North America.
After more than 50 hours of deliberation, the 12-person jury was unconvinced by the prosecution's description of a complex airline bomb plot, finding only three of the defendants - Abdulla Ahmed Ali, Assad Sarwar and Tanvir Hussain - guilty of a lesser charge of conspiracy to commit murder.
The jury failed to reach a verdict on four other defendants and the eighth was found not guilty on all charges. Sentencing is due to take place later.
The trial had been closely watched in Britain, where police and secret services described the plot as potentially one of the deadliest ever hatched on British soil. US authorities said it could have killed as many people as the September 11, 2001 attacks on New York and Washington.
The British government praised Monday's verdict, but the fact only three of the eight were found guilty, and that the main charge failed to stand up, showed there was doubt in the minds of the jury about the full extent of the plot.
The prosecution had described Ali, 27, as the ringleader of the gang and presented evidence taken from him including a diary that contained what they said was a blueprint for an attack.
A memory stick owned by one of the suspects held detailed information about flights from Heathrow to US and Canadian cities, most of them departing between August and October 2006.
The bombs would have been made from liquid explosives based on hydrogen peroxide mixed with an organic component such as tang, a substance used to make soft drinks, prosecutors said.
Though Ali, Sarwar and Hussain admitted planning to carry out an attack, they said it was intended merely to be a publicity stunt designed to draw attention to videos they had made denouncing British and US foreign policy in Iraq. They said they had never intended to attack aircraft.
Liquid restrictions remain
After the plot was uncovered in August 2006, thousands of flights around the world were disrupted and new restrictions were introduced banning passengers from taking liquids on aircraft.
The British government said on Monday the restrictions would remain in place.
Liquids, gels and aerosols are only allowed in individual containers of 100ml which must be carried in one, transparent bag.