Murat Kurnaz, 24, who was released in August because of lack of evidence that he was involved in terrorist activities, said he endured many types of torture.

"From electric shocks to having one's head submerged in water, (subjection to) hunger and thirst, or being shackled and suspended," Kurnaz said, listing the alleged abuses he faced while a detainee at Camp X-Ray in Cuba.

A burly man with long reddish hair and a thick beard stretching down to his belly, Kurnaz spoke without emotion to CNN Turk television from his home in Bremen, northern Germany.

Tales of torture

"They tell you 'you are from Al-Qaeda' and when you say 'no' they give the (electric) current to your feet.... As you keep saying 'no' this goes on for two or three hours," he said, adding he had several times lost consciousness," Kurnaz said.

He claimed he was once shackled to a ceiling for "four or five days."

"They take you down in the mornings when a doctor comes to see whether you can endure more," he said. "They let you sit when the interrogator comes.... They take you down about three times a day so you do not die."

Kurnaz also alleged prisoners were locked up in cells into which frigid or hot air was pumped.

"I saw several people die," he said. "Sometimes I thought I could no longer stand it and would also die."

He claimed he was once left without food for 20 days and spoke of psychological abuse, including "religious insults" such as the Koran being kicked on the ground.

Arrested, but still no proof of terrorist links

A Turkish citizen with permanent residency in Germany, Kurnaz was arrested in Pakistan after the September 11, 2001 attacks and turned over to US forces, who took him to a prison in the Afghan city of Kandahar before transferring him to Guantanamo in 2002.

He says he went to Pakistan to visit holy places and take religious courses.

'Germany conspired with US'

German prosecutors have also dropped a long-running probe into Kurnaz on the grounds they failed to find any firm proof he belonged to a terrorist group.

Kurnaz has insisted throughout he was innocent, and on his return to Germany accused the government of former chancellor Gerhard Schroeder of colluding with the US forces.

Around 450 prisoners are being held at Guantanamo Bay -- some for years -- without charges being brought. Human rights lawyers have brought suits on behalf of the detainees, many of them picked up as suspected Al-Qaeda or Taliban fighters from Afghanistan.

Rumsfeld sued over Guantanamo

Kurnaz's statements come at a time when civil rights lawyers are hoping German prosecutors will open a war crimes investigation into the role of outgoing US Secretary of Defense Donald Rumsfeld and a host of other officials in the abuse at Iraq's Abu Ghraib prison and Guantanamo Bay.

The suit is brought on behalf of 12 alleged torture victims including Mohamad al-Qahtani, a Saudi being held at the U.S. military prison in Guantanamo Bay, Cuba, who has been identified by the US as a would-be participant in the Sept. 11 attacks.

After FBI agents raised concerns, military investigators began reviewing the case and in July 2005 said they confirmed abusive and degrading treatment.

German prosecutors already declined to investigate a more limited suit in 2004, arguing that it was up to the U.S. to launch any inquiry.

The attorneys involved think they have a better case this time. They argue that Rumsfeld's resignation last week means prosecutors may be under less political pressure to shun the case.

Wolfgang Kaleck, the German attorney who is leading the litigation, said the suit's backers would appeal if prosecutors refuse to take up the case, and raised the prospect of further attempts in other European countries.