Britain's top anti-terrorism police chief has tendered his resignation following a security blunder.
London Mayor Boris Johnson told BBC radio he had accepted Assistant Metropolitan Police Commissioner Bob Quick's resignation with 'great reluctance and sadness'.
Mr Quick has said he deeply regretted the disruption caused to colleagues when he inadvertently revealed details of a counter-terrorism operation.
He was pictured clutching sensitive documents as he arrived in Downing Street yesterday.
Among a large bundle of papers under his arm was a white document clearly marked 'secret' and carrying an outline briefing on an ongoing counter-terrorism operation.
The information included the names of several senior officers, locations and details about the nature of the overseas threat.
The blunder triggered premature anti-terror arrests yesterday evening.
12 men, suspected of links with al-Qaeda, were arrested in the UK after a series of raids.
Police from Greater Manchester, Lancashire and Merseyside forces were involved in the swoops.
The arrests were made at addresses in Cheetham Hill, Manchester, John Moores University, Liverpool, and Clitheroe in Lancashire.
