British police and counter-intelligence agents arrested 12 suspected terrorists in multiple raids in north-west England on Wednesday after details of the secret operation leaked to the press abroad.

The Metropolitan Police Service (MPS) and MI5, Britain's counter- intelligence agency, were forced to make the raids and arrests ahead of schedule because photos of the document showing some details of the secret operation were published in overseas newspapers.

The photos came from local photographers who shot the documents being carelessly held by MPS Assistant Commissioner and counter-terrorism chief Bob Quick under his arm while he was walking to the office of the prime minister.

Authorities deemed the plan to be compromised so the arrests were made early. Those arrested included 10 men of Pakistani origin and a student at Liverpool's John Moores University.

The suspects are believed to be plotting a bombing spree with a Manchester City nightclub or shopping complex as among the targets.

Meanwhile, Quick has apologized to his boss and colleagues at MPS, which is also known as Scotland Yard, for the blunder. "Assistant Commissioner Quick accepts he made a mistake on leaving a sensitive document on open view and deeply regrets it," said a Scotland Yard spokesman, according to Sky.com.