Nearly a dozen detainees at the Guantanamo Bay prison camp contend they were wrongly imprisoned after repeated abuse by U.S. troops in Afghanistan and Pakistan, including beatings with chains, electric shock and sodomy, their lawyer said Monday.

“These are classic stories of men who ended up in Guantanamo by mistake,” said attorney Tom Wilner, who represents 11 Kuwaiti prisoners held in the detention center at the U.S. Navy base in eastern Cuba.

Most of his clients say they falsely confessed to belonging to Afghanistan’s ousted Taliban regime or the al-Qaida terror network as a way to stop the abuse, Wilner said. He said one is too angry over his treatment to discuss details of his case, but all argue their detentions are unjustified.

Human rights groups and defense lawyers have long charged that some information used as the basis for incarcerations at Guantanamo Bay resulted from abuse or torture. Many of the 545 prisoners there have been held for more than three years. About 150 have been let go, but officials have not given explanations for their release.

The government has denied using torture, but multiple investigations into abuse at detention camps in Afghanistan and Guantanamo are under way. It is not clear whether some of the men’s statements could be dismissed if investigators confirm there was abuse during interrogations.

Maj. Michael Shavers, a Pentagon spokesman, said all “credible” abuse allegations are investigated, but he suggested the Kuwaitis’ claims were consistent with al-Qaida tactics to falsely allege abuse.

Although most of 11 Kuwaitis say physical abuse stopped once they arrived at Guantanamo, all complain of mistreatment, such as being locked in cells with scant reading materials and little information on the outside world, Wilner said in a conference call.