The four remaining Britons detained in Guantanamo Bay are to be returned in the next few weeks, Foreign Secretary Jack Straw announced today.
Once back in Britain, the police will consider whether to arrest them for questioning in connection with "possible terrorist activity," he told the Commons.
The move follows "intensive and complex discussions" with the US to address their security concerns.
The families of the four - Moazzam Begg from Birmingham, Feroz Abbasi, from Croydon, south London, Martin Mubanga, from Wembley, north west London and Richard Belmar, from St John's Wood, north west London - were told of the decision earlier today.
In a statement, Mr Straw recalled that the men were among those detained after the "worst terrorist atrocity which the US, the UK and indeed the world have ever suffered" - the September 11 attacks on America.
About 200 detainees had already been released from Guantanamo Bay. The US Government believes a number had "returned to terrorism, demonstrating the dilemma faced by the US in considering such releases".
Five of the nine British detainees at Guantanamo Bay were returned last March and there has been high-level discussions since then, involving the Prime Minister among others, to get the remaining four released.
"The four men will be returned in the next few weeks," he said. "Once they are back in the UK, the police will consider whether to arrest them under the Terrorism Act 2000 for questioning in connection with possible terrorist activity.
"Any subsequent action will be a matter for the police and the Crown Prosecution Service."
Mr Straw told the Commons: "I should like to assure the House that every practical step will be taken by the relevant UK authorities to maintain national security and to protect public safety."
Throughout the period of detention, the Government had sought to "balance the need to safeguard the interests of Britons detained overseas with our duty to meet the threat from international terrorism.
"Working with our allies, we will continue resolutely to defend these rights through a robust and determined approach to combating terrorism and its networks of support wherever it is to be found," he pledged.