Twelve suspected Islamic militants were arrested in a joint police and MI5 operation last night following an extraordinary security leak by Britain's most senior anti-terrorism chief.
Assistant commissioner Bob Quick was left facing calls for his resignation after he was caught on camera clutching sensitive documents as he arrived at Downing Street yesterday.
Dozens of officers from Greater Manchester Police, Merseyside and Lancashire were then ordered to search addresses in the North-west, dramatically seizing suspects outside the library of Liverpool's John Moores University. Other raids took place in Manchester, Lancaster and Clitheroe where 100 officers swooped on a Homebase store and arrested two security guards.
The suspects, who are of British and Pakistani origin, were arrested after what sources said was a long-term and ongoing surveillance operation into a plot to carry out bomb attacks in the UK.
The raids were brought forward after Mr Quick was pictured holding a white document bearing the word "secret". Pictures of him arriving at No 10 were broadcast on news channels and published on newspaper websites. The Ministry of Defence urgently issued a D-Notice designed to safeguard national security, which prevented media organisations revealing details of the documents. But by the time it was circulated the images had already made their way across the globe.
The Shadow Home Secretary Chris Grayling described the incident as, "an extraordinary and very alarming lapse". "It's the kind of error that Britain's most senior anti-terrorist officer simply can't afford to make, and it will lead to serious questions about his judgement and about his ability to do his job properly," he said.
Mr Quick later apologised to the Metropolitan Police Commissioner, Sir Paul Stephenson, saying he "deeply regretted" his actions. A Scotland Yard spokesman added: "Assistant commissioner Quick accepts he made a mistake on leaving a sensitive document on open view. He has apologised to the Commissioner and colleagues."
The Home Secretary Jacqui Smith said: "I want to congratulate Greater Manchester, Merseyside and Lancashire police forces for conducting a successful anti-terrorism operation which has resulted in 12 arrests at a number of locations in the northwest of England. The decision to take such action was an operational matter for the police and the Security Service but the Prime Minister and I were kept fully appraised of developments.
"While this investigation is ongoing it would, of course, be inappropriate to comment further."
According to one Whitehall source, there had been an ongoing security operation under way in the North-west for some time. It is highly unusual for such sensitive operations to be carried out at the height of rush-hour traffic, as they were yesterday. Students were ordered to stay away from the building's windows as a group of men were tackled before being led away. One witness said: "There was shouting by the police telling them [the suspects] to get on the floor. Everybody was panicking."