Gitanjali Gutierrez, the Information Commissioner, has recalled how shocked she was at the situation in Guantánamo Bay when she became one of the first human rights lawyers to visit the prison where she said the United States engaged in torture.

With the detention facility first taking prisoners — in the aftermath of the 9/11 attacks and subsequent US invasion of Afghanistan — 21 years ago this week, Ms Gutierrez said she was surprised it was still open and holding 35 inmates.

The remaining detainees should either be put on trial as soon as possible or returned to their home countries, she said.

Ms Gutierrez visited Guantánamo Bay on a number of occasions between 2004 and 2009 when she worked as a human rights lawyer.

Recalling her visits to the US base on the eastern tip of Cuba, Ms Gutierrez said: “Certainly it was troubling and disturbing to see the US military maintaining a facility like that, knowing what was happening there was not legal.

“The lack of legal representation for the detainees was shocking, it was very sobering.

“Prior to going to Guantánamo Bay, I had received correspondence from detainees, so I had some sense of the isolation and the conditions they were in.”

Ms Gutierrez said what was happening at the US facility amounted to torture.

“The US military has admitted to that. The US military engaged in what they called ‘enhanced interrogation’, which actually constituted torture under international law guidelines.

“Every time I came back from there, I came back recommitted to working on the legal cases.”

Ms Gutierrez, who worked for the Centre for Constitutional Rights in New York during the time she was visiting Guantánamo Bay, said its closure as a detention facility was long overdue.

“I am surprised it is still open. And now it seems like there is a just a political barrier to removing the last 35 men out of there.

“Either charge them if there is evidence and get on with it. If not, then repatriation options should be looked at.”

Human rights organisations such as Amnesty International have long condemned practices used by the US military at the facility such as waterboarding prisoners, sleep deprivation and holding them in indefinite detention without trial.

Guantánamo Bay has held some 780 prisoners since January 2002, when it was established as a prison camp by George W. Bush, then the President of the United States.

His successor in the White House, Barack Obama, said that he would close it , but met stiff opposition in Congress.

President Joe Biden has said he wants the facility shut before he leaves office.

When Ms Gutierrez was appointed as Bermuda’s Information Commissioner in 2015, George Fergusson, then the Governor, said she had “a distinguished record as a lawyer dealing with issues of public access to information in the US and, to some extent, the UK”.