Britain tonight moved to deport nine men arrested earlier this month following one of the country's biggest anti-terror operations since the July 7 attacks in 2005.

The men have not been charged with any offences nearly two weeks after being arrested in raids across Greater Manchester, Liverpool and Lancashire. Two other men remain in custody. The nine men, aged between 22 and 38, were tonight released by Greater Manchester police into the custody of the UK Borders Agency (UKBA) in preparation for deportation to Pakistan.

A Home Office spokesman said: "We are seeking to remove these individuals on grounds of national security. The government's highest priority is to protect public safety. Where a foreign national poses a threat to this country we will seek to exclude or to deport, where this is appropriate."

The arrests were mired in controversy as the operation had to be rushed forward following an embarrassing security leak by Assistant Commissioner Bob Quick, the then head of Scotland Yard's specialist operations wing.

Quick was photographed clutching sensitive documents as he arrived in Downing Street. Clearly visible on top of a large bundle of papers under his arm was a white document marked "secret" that carried an outline for briefing on a current counter-terrorism operation.

Realising the existence of the ­photos of the ­document – which included the names of several senior officers, sensitive locations and details about the nature of the overseas threat – a "D notice" was imposed by the government to restrict the media from revealing the contents of the picture. Quick resigned days after the arrests and the security blunder.

Counterterrorism officials at the time of the arrests said they believed an alleged al-Qaida terror plot against the UK, designed to cause mass casualties, was to have been carried out within days. Twelve men were arrested. Eleven of them were Pakistani nationals, 10 of whom were on student visas. A twelfth man was transferred to immigration officials earlier this month.

A Greater Manchester Police spokeswoman (GMP) tonight said that searches are continuing at a property in Galsworthy Avenue, Cheetham Hill, Manchester.

The GMP spokeswoman said: "Protecting the public is the main focus of the police. These arrests were carried out after a number of UK agencies gathered information that indicated a potential risk to public safety.

"Officers are continuing to review a large amount of information gathered as part of this investigation.

"Investigations of this nature are extremely complex. We remain grateful to the support and cooperation of the communities affected."

Officials have not released details about the reported terror plot but the prime minister, Gordon Brown, called it "very big."

The 12 men were taken at seven locations across north-west England, and at least another eight addresses in the region were searched. Scores of students witnessed one arrest, carried out at Liverpool John Moores University.

The arrests were carried out in daylight because of the security leak, in direct ­contravention of the usual practice of arresting people while they sleep.

Moves to deport the nine men could lead to friction between Britain and Pakistan. Earlier this month the head of Pakistan's interior ministry, Rehman Malik, said Britain should charge and prosecute the suspects if it has enough evidence.