THE British bomb plotters could have been preparing to launch their first attacks as soon as next week, it was claimed yesterday.
According to unconfirmed reports, the 23 people now in custody had purchased airline tickets on flights bound for cities in the United States next Wednesday, 16 August.
Up to three flights would have been bombed high above the Atlantic using explosive devices concealed in drinks and personal items, including cameras and music players.
Because the planes would fall into the sea, there would be little or no trace of what downed them, potentially leaving the plotters free to launch another, similar wave of attacks days or even weeks later.
According to US media reports, the would-be bombers were planning a "dry run" of their attacks this weekend, with the real thing coming next week.
Evidence suggesting the tickets for next week's flights had been booked is believed to have been found by police officers searching properties associated with the arrested conspirators.
However, well-placed intelligence sources have told The Scotsman that the "trigger" for the arrests mounted this week was not the purchase of airline tickets.
At the time the arrests were ordered, officials did not believe the plotters had gone as far as booking themselves on flights.
The apparent contradiction between US and British sources over the operation is not the first. There is also a difference over American claims that five more suspects are being sought, something that British sources dismiss.
Privately, British security officials are growing exasperated at the flow of leaked information from the US.
In particular, the ABC television network yesterday reported that MI5 had actually penetrated the UK terror cell, placing an undercover agent inside the plot as part of work known as Operation Overt.
While MI5 is known to run covert agents in the British Muslim community, their work is among the most sensitive in British intelligence circles, and normally close relations between UK and US agencies have not been helped by the ABC report, which appeared to originate with US law enforcement officials.
Reports circulating in the US media yesterday also suggested that the entire operation against the plotters began last summer with an unsolicited tip to MI5 from a British Muslim only days after last July's suicide bomb attacks on London.
According to US officials who briefed the Washington Post, the unnamed informant had grown concerned about the actions of his neighbours and contacted police with his suspicions.
The information was in turn passed to the Security Service, which began an initial background check on a small number of people who were among those arrested on Wednesday.
While British officials confirm that the background surveillance began last summer, they refuse to disclose the precise reason the operation started.
Another version of events in circulation suggests that the origins of the operation lie in information extracted from senior al-Qaeda figures arrested in Pakistan early last year.