An Iranian detained at the US naval base at Guantanamo Bay in Cuba has refused to appear before a US military tribunal to review his case.
The cases of all prisoners at Guantanamo are being reviewed
He is the sixth detainee out of 11 to refuse to participate since the hearings began last week.
The tribunals follow a US Supreme Court ruling that the prisoners have the right to challenge their detentions.
Human rights groups have criticised the hearings because the detainees do not have access to lawyers.
The 25-year-old Iranian's case was the only one to be heard on Friday.
He apparently relayed his decision through a military officer who was assigned to be his representative.
"He dropped out," the officer, an Air Force lieutenant colonel, was quoted by the Associated Press as saying.
"He said, 'I don't want to participate anymore'."
The US Defense Department said the man was accused of fighting for the Taleban in Afghanistan against US forces and its allies.
The hearing went ahead in his absence. AP said it lasted 13 minutes before reporters were asked to leave so classified information could be discussed in a closed session.
Earlier in the week three Yemenis, a Saudi and a Moroccan refused to appear at their hearings.
On Thursday, the BBC's Nick Childs was one of a small group of reporters allowed to witness the appearance of two Afghan men at their hearings in a windowless, cramped room at Guantanamo.
The men, both handcuffed and shackled, admitted they were with the Taleban but said they never fought US forces. Their requests to call witnesses were denied.
This is the first time any of the 600 or so detainees, who have been held without trial or access to lawyers for more than two years, have been allowed any form of hearing.
Initial results could be given by next week, US officials say.
Human rights groups say the process is inadequate because the detainees are not allowed lawyers, and the three military officers sitting on each panel can not be considered to be impartial.
But the man overseeing the process, Gordon England, has defended the system, saying it derives from the Geneva Convention.