Mr Obama also announced a new process for continuing to hold those detainees not charged or convicted but deemed too dangerous to free. He said the measures would "broaden our ability to bring terrorists to justice".

Mr Obama had pledged in January 2009 to close the prison within a year. "The American system of justice is a key part of our arsenal in the war against al-Qaeda and its affiliates," Mr Obama said in a statement.

He added that military commissions "ensure that our security and our values are strengthened". US Defence Secretary Robert Gates issued an order on Monday revoking his previous suspension on the "swearing and referring of new charges in the military commissions".

New military commissions at the prison, which holds a number of top suspects from the 9/11 attacks and other strikes against the US, have been suspended since January 2009.

The White House said Mr Obama remained committed to the eventual closure of Guantanamo Bay.