SAN JUAN, Puerto Rico -- U.S. military officials at Guantánamo Bay are defending conditions in a disciplinary block known as “Five Echo,” taking the unusual step Friday of releasing photos of a section of the jail not typically shown to outsiders.

Lawyers for detainees say the cells are too small, toilets inadequate, lights overly bright and its air foul, and they call it inhumane to keep detainees there for 22 hours a day, especially when they have not been convicted of a crime.

David Remes, a Washington-based attorney who represents three prisoners who have been held in Five Echo, said this week that the disciplinary unit appears to violate the Geneva Conventions.

“Five Echo is really a throwback to the bad old days at Guantánamo,” Remes said.

Guantánamo Bay officials said Five Echo is by its nature a worse place to be imprisoned than in the communal blocks where most detainees at Guantánamo are now held, but the military disputed the assertions that its conditions violate the Geneva Conventions.

“It is safe, humane and meets all the regulations,” Army Col. Donnie Thomas, commander of the guard force at the prison, said of Five Echo during a telephone interview from the U.S. base in Cuba.

The photos released to The Associated Press show empty cells with steel, pale green walls and a translucent, rectangular window near the ceiling covered in steel mesh. The military said the cells have about half the space of those in nearby Camp Five. The cells have a squat toilet in the floor, instead of a standard prison toilet found elsewhere in the prison.

Lawyers said that they did not believe any photos of the unit had been released previously and that the military has been secretive about the section of the prison.

Guantánamo, which is now approaching its 10th anniversary as a detention center for men suspected of links to al-Qaida and the Taliban, holds about 170 men in three camps. President Barack Obama vowed to close the prison upon taking office but has been thwarted by Congress, which has blocked efforts to move detainees to the U.S.

The 15 most notorious prisoners, including the self-proclaimed mastermind of the 9/11 attack, are held in a top-secret section known as Camp Seven. Little is known about that area and even its location on the base is classified.

About 80 percent of the detainees are held in Camp Six, where they are free to congregate with each other in a communal setting for 20 hours a day, and they have access to games, classes and 20 channels of cable television. The military has credited creation of this communal block for a sharp drop in prisoners’ protests, hunger strikes and assaults on guards.

Camp Five is now largely used for detainees who attack a guard or otherwise violate the rules in Camp Six and are deemed “noncompliant.” It has capacity for about 100 prisoners but is less than half full.

Five Echo originally was created in 2007 as an overflow disciplinary section, but now is used as an “extension” of Camp Five, Thomas said.

Thomas declined to disclose the criteria for the use of Five Echo. He said it was empty Thursday, the day of the phone interview, but added that he could resume using it at any time at his discretion. He declined to say when it last held detainees.

Five Echo has not been included in media tours of the Guantánamo jail provided for members of the media, and officials have previously provided little information about the unit.

Remes, a lawyer for a number of prisoners, said he drew a diagram and collected other details following a meeting with one of his clients, a Saudi national and British resident named Shaker Aamer who has been held in Five Echo. But he said the notes were deemed classified by a government review team and he is not permitted to release them.

Ramzi Kassem, a lawyer and law professor who also represents Aamer, said the detainee described abysmal conditions in Five Echo. He said the squat toilet is difficult to use, there are foul odors, bright lights shine on detainees and air conditioners keep it extremely cold.

“It is decrepit, filthy and disgusting. Those are the words he used to describe it,” said Kassem, a professor of law at the City University of New York.

Aamer also told him there is not enough room in Five Echo for the Muslim prisoners to do their prayers. Detainees in the block are allowed two hours a day out of the cells for recreation.

Kassem said conditions are akin to those of a Supermax prison in the United States.

Thomas denied the lights are overly bright and said the toilets are adequate and conditions overall are humane.

“Quite frankly, detainees make the determination where they live,” he said. “If they are compliant they live in Camp six. If they are noncompliant they live in Camp 5.”