Afghan forces arrested three Americans, including a purported former Green Beret, after raiding a jail they were allegedly running in the Afghan capital and finding prisoners hanging from their feet, officials said Thursday.

The U.S. military, facing a widening inquiry into prisoner abuse, quickly distanced itself from the three, who had been posing as American agents before being detained Monday. State Department spokesman Richard Boucher said Thursday, "The U.S. government does not employ or sponsor these men."

Afghan officials also dismissed claims by the apparent ringleader, Jonathan K. Idema, that he was a special adviser to their security forces, saying the three had posed as military agents on a self-appointed hunt for terrorists.

The Americans and four Afghans who were detained along with them "formed a group and pretended they were fighting terrorism," Interior Minister Ali Ahmad Jalali said. "They arrested eight people from across Kabul and put them in their jail."

Another Afghan security official said that intelligence and police officials who raided the group's house Monday found the prisoners strung up by their feet.

"They were hanging upside down," said the official, who spoke on condition of anonymity. He said a report showed the men also were beaten.

Jalali said the Americans had no "legal link" to any Afghan or other authorities.

Still, officials said they were seen regularly around Kabul wearing military uniforms and armed with assault rifles.

Idema, described in media reports as an ex-Special Forces operative known as "Jack," first appeared in Afghanistan in late 2001, when U.S. and allied Afghan forces routed the Taliban.

He featured prominently in a top-selling book, "The Hunt for Bin Laden," which says he fought for 10 months alongside the anti-Taliban Northern Alliance.

He also offered his services to Western television networks.

On Thursday in Washington, Boucher confirmed that Idema was one of the men in custody and identified another as Brent Bennett. He gave no other details.

Lawrence Di Rita, the Pentagon's chief spokesman, said he did not know which service branch Idema had been in. "He has a military background. But I don't know to what extent, how long he was in the service. I don't have those details."