WASHINGTON: A man from Yemen held at the US-run prison in Guantanamo for more than seven years without charge was found dead in an apparent suicide, the US military said on Tuesday.

The 31-year-old inmate was identified as Muhammad Ahmad Abdallah Salih, also known as Al-Hanashi. He had been held at Guantanamo since February 2002, US Southern Command said in a statement.

It was the fifth reported suicide at the controversial “war on terror” prison since the center opened at the remote US naval base in southeast Cuba in 2002.

“While conducting routine checks, the guards found the detainee unresponsive and not breathing,” the US statement said. “Medical personnel were immediately summoned by the guard force. After extensive lifesaving measures had been exhausted, the detainee was pronounced dead by a physician,” it said.

The suspected suicide occurred late Monday evening and the Naval Criminal Investigative Service had opened an investigation to determine the cause and circumstances surrounding the death.

US Southern Command offered no other details of the incident. It said the remains will be repatriated to Yemen after an autopsy.

Salih was never charged by special military tribunals set up to try top terror suspects at Guantanamo. The US military alleged that intelligence reports indicated he had fought alongside the Taleban in Afghanistan and was captured in Mazar-e-Sharif.

The American Civil Liberties Union, an advocacy group, called for a full investigation into Salih’s death. “There must be an immediate, independent and transparent investigation into the circumstances surrounding this apparent suicide and the conditions of confinement at Guantanamo,” said ACLU lawyer Ben Wizner.

Mohammed Albasha, spokesman of the Embassy of Yemen in Washington, said that his country was saddened to learn the news.

An embassy representative was flying to Guantanamo and will work “closely with the US government” to quickly repatriate the body. “We extend our deepest condolences to the family of the deceased,” Albasha said in a statement.

“In addition, this incident demonstrates the urgency of closing the detention facility at Guantanamo Bay.”

Yemen “is looking forward to cooperate closely with the US administration to expedite President (Barack) Obama’s decision to close Guantanamo,” Albasha said.