Government has three weeks to release Afghan man held without charge since 2002.
The team examining US detention policy has not reached a decision on whether to make a formal recommendation on such a proposal, the official said.
The task force’s investigation follows a pledge by Obama to close the prison at Guantanamo Bay, Cuba.
Obama said that he wants the prison to be closed by January 2010 but opposition politicians have said that they are against transferring the jail’s 240 inmates to the US to continue their detention or stand trial.
So far 11 people at Guantanamo have been charged with crimes, but US military prosecutors say they have a strong case against 66 detainees who are being held without charge.
Washington has been internationally criticised for its detention policy in Guantanamo, particularly for keeping detainees at the prison for protracted periods without charge and for controversial interrogation techniques that some have called torture.
Obama has suspended prosecutions at the prison, which was set up after the September 11, 2001 attacks, pending the completion of a review into the first US war crimes tribunals since the second world war.