The Pentagon announced Thursday the transfer of Pakistani detainee Majeed Khan - who revealed horrific details of his torture at the hands of the CIA after the September 11, 2001 attacks - from Guantanamo Bay prison in Cuba to Belize.

According to US officials, Khan, 42, pleaded guilty in 2012 to conspiring with al-Qaeda members responsible for the 2001 attacks to commit murder and provide material support for terrorism and espionage, and has been a witness for the government ever since.

Khan was captured in Pakistan and held in a CIA "black site" from 2003 to 2006, before being imprisoned in the detention camp at the US Naval Base at Guantanamo Bay.

In a statement issued by his legal team, Khan welcomed what he called "another chance at life," and said, "I deeply regret the things I did many years ago. I took responsibility and tried to make up for it. I still ask forgiveness from God and those I hurt. I'm really sorry."

Khan is the first detainee in Guantanamo to be released since last October and resettled in a third country, leaving 34 detainees in the facility, including 20 US officials say they are already eligible for transfer to other countries, and earlier the number of detainees in Guantanamo reached 800.

There were 40 detainees there when Democratic President Joe Biden took office in 2021, and Biden has said he hopes to close the facility.

The law prohibits the federal government from transferring Guantanamo detainees to mainland US prisons.

"We remain committed to a measured and comprehensive process focused on responsibly reducing the number of detainees at Guantanamo Bay and ultimately closing the facility," White House press secretary Karen Jean-Pierre told reporters.

Eamon Courtenay, Belize's foreign minister, said his country's government had accepted Khan's transfer and the US government had paid the costs.

"Mr. Khan is not a terrorist, he has completely recanted his actions and accepted responsibility for them, and asks God for forgiveness," Courtenay said at a press conference in Belize (located in Central America).

Courtenay - who met Khan upon his arrival in Belize - confirmed that he was free to live the rest of his life there if he wanted.

Khan had read a 39-page statement to a US military commission for sentencing in 2021 describing his treatment at the CIA site, and talking about being beaten, waterboarded and raped.

He said he was hung by his hands for several days, naked except for a headscarf, and that the guards there "threw ice water on my naked body every hour or two, and put a fan to blow air directly at me."

He also stated that he was deprived of sleep and food, and remained isolated and tied in a cell, while music played 24 hours a day, and he explained that this lasted 3 years since his arrest in Karachi in 2003 until his transfer to Guantanamo in 2006.

The Pentagon said Defense Secretary Lloyd Austin notified lawmakers of his intention to transfer Khan last year.