The Saudi-born British resident has never been charged or faced trial in the 10 years he has been held in the controversial U.S. detention facility, The Daily Telegraph said Wednesday.
The Scotsman newspaper reported that leaked U.S. files show the United States believes Aamer, 43, met al-Qaida founder Osama bin Laden in Afghanistan and has an association with convicted Sept. 11, 2001, conspirator Zacarias Moussaoui.
Supporters say the claims are false.
Aamer was cleared for release by the Bush administration in June 2007.
Aamer's attorney, Clive Stafford Smith, told Britain's Independent newspaper he fears his client will die before any charges are actually filed against him.
A spokesman from the British Foreign and Commonwealth Office said Aamer's case has been raised again with U.S. Secretary of State Hillary Clinton, The Daily Telegraph said.