The Obama administration on Monday repatriated to London its first Guantánamo detainee -- a chronic hunger striker who has long claimed torture -- on the same day a senior Navy official declared the controversial prison camps humane but wracked by anxiety over the future.

''Everyone knows the camps will close. They are expecting movement,'' said Adm. Patrick Walsh, deputy Chief of Naval Operations.

Walsh urged the administration to fund more improvements at the prison camp compound even as it empties it.

He advocated more communal prayer time for captives confined to solitary cells and videotaping the camps and interrogation chambers to ensure accountability. He also recommended letting family members have visits to the prison camps, as well as adding video teleconferencing to already approved annual phone calls from home.

The activity signaled the earliest phases of implementation of President Barack Obama's Jan. 22 order to empty the camps in southeast Cuba of all 240 detainees within a year.

Some would be resettled abroad, others brought to the United States for trials through case-by-case review.

Last week, Attorney General Eric Holder named a director of the review Task Force and by Monday Binyam Mohamed, once accused of war crimes, stepped off a plane at a British military base, a free man.

At about the same time, Holder was bound for Guantánamo on his first-ever visit.

A frequent hunger striker, Mohammed, 30, had for years accused the Bush administration of outsourcing his 2002 interrogation to torture in Morocco, notably extracting false confessions of complicity in a ''dirty bomb'' plot by cutting his genitals with a scalpel.

Monday, he looked fit in skullcap and sweater in news photos of his arrival to Britain, the nation that had granted him residency as a teen after his family fled his native Ethiopia.

'Before this ordeal, `torture' was an abstract word to me,'' he said in a statement. ``It is still difficult for me to believe that I was abducted, hauled from one country to the next, and tortured in medieval ways all orchestrated by the United States government.''

He said he wasn't yet ``physically nor mentally capable of facing the media.''

A Bush administration era architect of Guantánamo policy resurrected the dirty bomb allegation and accused Obama of ``clearly taking actions that may endanger the United States and our national interests.''

Retired Navy Cmdr. Kirk Lippold, whose destroyer the USS Cole was struck by suicide bombers in October 2000, said in a statement issued by the advocacy group Military Families United: ``Americans must now be very watchful of every action the Obama administration takes in war on terror.''

Walsh, meantime, told a Pentagon press conference that he found the camps Geneva Conventions compliant.

The admiral said his team spent 13 days at the base, questioned a dozen detainees and about 100 guards and other staff to validate persistent Pentagon claims that the prison camps are humane.

Some detainees alleged abuse, he said, specifically citing a case in which guards tackled and shackled and took an unnamed hunger-striker from his cell to a tube-feeding in a restraint chair. But he said an independent examination of videotapes and the record justified the force.

The New York Center for Constitutional Rights, which defends dozens of detainees, disputed the finding. It cited recent detainee claims of unwarranted force and long periods of mind-numbing isolation that no U.S. troop held as a prisoner-of-war would consider humane.

Staff attorney Pardiss Kebriaei, who visited the camps in January, accused the admiral of conducting ``at best an incomplete review, at worst a dishonest one.''

The admiral described ''increased tension and anxiety'' about the detainees' future. Everyone knew about the President's closure order and also about the plight of 17 Uighurs -- Muslim citizens of China still at the base while the U.S. seeks third-country to take them.

The men are housed at a separate prison camp but they symbolize the inability, so far, of the U.S. government to resettle them because the Bush administration had refused to move them to American soil and allies had so far spurned requests to provide them sanctuary.