Starting with the arrival from Afghanistan of the first group of 20 shackled and masked detainees on 11 January 2002, the United States has never released the names and nationalities of all the prisoners at the controversial camp. While incomplete, the new list was the most thorough made public to date.
The Pentagon released at 6.40pm (2340 GMT) on Friday night more than 5000 pages of documents relating to hearings conducted at the US naval base at Guantanamo Bay, Cuba, by military panels reviewing the cases of detainees.
Curt Goering, a senior official with Amnesty International USA, called on the Pentagon to release a complete list of detainees at Guantanamo as well as facilities in Afghanistan and elsewhere.
"It is like kicking and screaming and pulling teeth to get any piece of information" on detainees from the Pentagon, Goering said.
Only 10 of the detainees at Guantanamo have been charged with a crime, and human rights activists have condemned the indefinite detentions and the prisoners' lack of legal rights.
UN rights investigators have urged Washington to close the prison camp.
US soldiers talk to a prisoner at
Camp Delta in February
Bryan Whitman, a senior Pentagon spokesman, said the documents contained the names and nationalities of about 317 detainees.
Whitman said the Pentagon would not release this data on all 490 detainees because of concern about "harm to the detainees".
"There is a concern that there could be potential harm to the detainees if personal information such as their name was a matter of public record," he said.
US District Judge Jed Rakoff in February ordered the Defence Department to release transcripts of detainee hearings by Friday as part of a lawsuit filed by the Associated Press.
Because the lawsuit did not seek data on detainees who refused to take part in the military hearings, Whitman said, their names and nationalities would not be released. Rights lawyers said the Pentagon deserved little credit.
"If Judge Rakoff had not ordered the release of these names, the department would never have released them," said Bill Goodman, legal director for the New York-based Centre for Constitutional Rights, which represents numerous detainees.
"And that just adds to the levels of secrecy that surround the detentions at Guantanamo, the lack of transparency and the overall absence of anything that would resemble what Americans have gotten used to describing as justice or due process."
Camp X-Ray succumbs to the
elements after it was closed in 2002
The US has identified some detainees in legal documents, including the 10 who have been charged. The names of others have become public by their relatives or lawyers.
Former detainees, lawyers representing inmates and UN human rights investigators have accused the US of using torture at Guantanamo, and US government documents have shown FBI agents came to the same conclusion.
The Pentagon says the detainees are treated humanely and not tortured. The US classifies the men as enemy combatants and not prisoners of war, thus denying them rights afforded to POWs under the Geneva Conventions.
The US opened the Guantanamo prison three months after invading Afghanistan to topple its Taliban rulers who had harboured al-Qaida, responsible for the September 11 attacks. Most of the detainees were captured in Afghanistan, and most are believed to be Muslim.