The American Civil Liberties Union and Amnesty International are calling for an independent investigation into the death of detainees at Guantanamo Bay after the U.S. military reported another death at the detention facility on Wednesday night.

"This latest death highlights the immediate need for a full and independent inquiry into deaths at Guantanamo," Jamil Dakwar, director of the ACLU Human Rights Program, said. "It also underscores the tragic consequences of indefinite detention and unfair trials of detainees."

A 37-year old Afghan detainee died at Guantanamo Bay in an apparent suicide, the U.S. military said in a statement.

The man, identified by one name, Inayatullah, was an admitted planner for Al-Qaeda terrorist operations, according to the Southern Command. He arrived in Guantanamo in September 2007. A spokeswoman for the detention center said he did not have a history of disciplinary problems and was "generally a compliant detainee."

Inayatullah was the eighth person to die at Guantanamo since the U.S. government started transferring prisoners there following the 2001 ouster of the Taliban in Afghanistan.

The Associated Press reported that he had tried to kill himself two other times and had been diagnosed with a mental illness.

"I will tell you as far as I'm concerned he never did a violent act, he never planned a violent act," Attorney Paul Rashkind told The Associated Press. "He was not a terrorist. His mental health issues made it difficult to address why he was there."

The Southern Command said the Naval Criminal Investigative Service will investigate the incident, something it does with all detainee deaths.

"Previous investigations carried out by this service into detainee deaths have lacked independence and transparency," said Susan Lee, Amnesty International’s Americas Programme Director.

The prisoner hanged himself with a bed linen in an exercise yard, according to the U.S. military.

"The families of those who have died at Guantánamo should also have access to remedy, including compensation, for any human rights violations to which their relatives were subjected during their years in U.S. custody, including arbitrary detention, torture or other cruel, inhuman or degrading treatment or punishment," Lee added.

With AFP.