LONDON (Reuters) - An African detainee held at the U.S. prison camp at Guantanamo Bay since he was a teenager has been released without charge after more than seven years in captivity, his lawyers said on Thursday.

A guard tower of Camp Delta is seen at the Guantanamo Bay Naval Station in Guantanamo Bay, Cuba September 4, 2007. REUTERS/Joe Skipper/Files

Mohammed El Gharani, a Chadian citizen, was freed five months after a U.S. federal judge ordered him released having reviewed the evidence against him and ruled that there was nothing to suggest he was ever an “enemy combatant.”

Lawyers for Gharani said he was the youngest detainee to be released from Guantanamo, having been seized in 2001 when he was 14.

But the Pentagon disputes his age, saying they believed he was now 23, and that there were others held at Guantanamo Bay over the past seven years who had been younger.

“Our records indicate that he is 23 and that he arrived at Guantanamo when he was 16,” said Navy Commander Jeffrey Gordon, a Pentagon spokesman. He said there was no birth certificate for Gharani but that his age had been established “by other means.”

Reprieve, a legal and human rights group that campaigned for Gharani’s release, said he had already returned to Chad.

“It is great news that Mohammed has at last been released, but he will never get back the teenage years that were spent in Guantanamo based on shamefully shoddy intelligence,” said Clive Stafford Smith, Gharani’s lawyer and the director of Reprieve.

“The idea that it took seven years and a federal judge to sort this out demonstrates just how failed an experiment Guantanamo Bay is.”

Gharani was seized in Pakistan in 2001 when a mosque he was attending was raided by Pakistan’s security forces. He was ultimately turned over to the U.S. military in Afghanistan and held at a prison at Bagram air force base outside Kabul.

Two months later he was transferred to Guantanamo Bay, where Reprieve said he was subjected to a range of abuses, including being kept tightly shackled to the ground in a hunched position for hours on end and subjected to loud music and strobe lights.

The U.S. government accused Gharani of staying in an al Qaeda-affiliated guest house in Afghanistan, of fighting in the battle of Tora Bora, serving as a courier for senior al Qaeda operatives, and being a member of a London-based al Qaeda cell.

But the government failed to prove any of the allegations in court and U.S. District Judge Richard Leon ruled in January that Gharani should be freed.

Most of the accusations were based on unreliable information given by other detainees at Guantanamo, Leon said.

Gharani’s release comes six months after U.S. President Barack Obama pledged to shut down Guantanamo within a year, one of the first declarations he made as president.

About 230 detainees remain at the prison, but the United States is struggling to find places to return them to.

Seventeen Uighurs, who come from China’s largely Muslim region of Xinjiang in the far west of the country, have been released in the past two days, with some set to go to Bermuda and others to the Micronesian island of Palau.