KABUL, Afghanistan -- 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 by their feet, officials said yesterday.

The U.S. military, facing a widening inquiry into prisoner abuse, quickly distanced itself from the three, who had been posing as U.S. agents before being detained Monday. State Department spokesman Richard Boucher yesterday said, "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 terrorist hunt.

The Americans and four Afghans 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 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 that the men also had been beaten.

Jalali said the Americans had no "legal link" to any Afghan or other authorities. Still, officials said they were regularly seen in Kabul, clad in 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 is 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, including an apparent training video about the al-Qaida terror network.

Yesterday, police gave an Associated Press reporter a business card apparently handed out by Idema. The card bears an Afghan flag with a small Stars-and-Stripes at its center and a Northern Alliance flag. "Special Adviser" is printed on the bottom, and "Jack" is scrawled in the Dari language at the top. None of the three phone numbers worked.

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

Pentagon chief spokesman Larry Di Rita said he didn't know in which branch Idema had served. "He has a military background. But I don't know to what extent, how long he was in the service."

One police official said Idema's group appeared to be behind the disappearance of a man in west Kabul three weeks ago. The missing man was identified as Abdul Latif, and his wife told authorities that she believed he had been seized by members of the NATO-led force that patrols the capital, said the police official, who spoke on condition of anonymity. He said three foreigners dressed in military uniforms this week returned to the house, where police confronted them.

He said a man called Jack told the officers that he had orders to arrest a terrorist before he could blow himself up in a government building. The three said they belonged to "an important network," but gave no other details, the police official said.

Jalali said all eight prisoners found imprisoned Monday were released.

There was no sign of Latif, however, at his house in a quiet Kabul residential street. Yesterday, uniformed Afghan intelligence officers refused to admit reporters into the house where the eight prisoners had been found. Residents said foreigners had lived there, and they had noticed nothing suspicious.