Watch video: terror raids in North West England

A huge MI5 and police counterterrorist operation against al-Qaeda suspects had to be brought forward at short notice last night after Scotland Yard’s counter-terrorism chief accidentally revealed a briefing document.

Twelve people were arrested, ten of them born in Pakistan, at eight separate addresses after a long covert surveillance operation involving MI5 and police from the North West Counter-Terrorism Unit was compromised.

Senior sources believe that there were plans to attack the Birdcage nightclub in Manchester city centre or the Trafford Centre shopping complex. The nightclub, which hosts cabaret and dancing showgirls, attracts thousands of people each week.

Detectives believe that the venue, near The Printworks entertainment complex, was being targeted as a “symbol of Western decadence”. The Trafford Centre in Manchester attracts 140,000 shoppers each weekend.

The operation was nearly blown when Assistant Commissioner Bob Quick walked up Downing Street holding a document marked “secret” with highly sensitive operational details visible to photographers.

The document, carried under his arm, revealed how many terrorist suspects were to be arrested, in which cities across the North West. It revealed that armed members of the Greater Manchester Police would force entry into a number of homes. The operation’s secret code headed the list of action that was to take place.

The assistant commissioner had been scheduled to see the Prime Minister and Jacqui Smith, the Home Secretary, about police reform in his capacity as a member of the Association of Chief Police Officers, but the document indicated that he was planning to outline to Gordon Brown that police raids were imminent.

Police sources indicated that the blunder could end Mr Quick’s career. A Scotland Yard source said: “It’s a hugely serious situation — he’s made a big blunder and the consequences have been huge. There is pressure on him tonight to step down.”

As soon as the photograph was circulated, MI5 and Scotland Yard took immediate steps to stop its publication, fearing that even a reference to Mr Quick’s arrival in Downing Street might tip off the suspects.

A rare D-notice — guidance issued from the Ministry of Defence to safeguard issues of national security — was slapped on media organisations.

However, the photograph of the document had already been distributed abroad, where the D-notice system carries no weight. Getty Images, which took the photograph, agreed to take it off its website, but foreign media organisations that have contracts with Getty had already received the picture, along with every national newspaper in Britain. A Californian magazine also had the picture.

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