The Army's investigation of prisoner abuse in Iraq has expanded to accusations that military interrogators with the California National Guard (search) beat up and choked detainees, authorities confirmed Thursday.

Members of the 223rd Military Intelligence Battalion, which returned from Iraq in March, are accused of abusing Iraqi prisoners last year at a detention facility in Samarra, north of Baghdad.

The accusations surfaced in an internal Army report obtained by The New York Times that listed the status of three dozen investigations. The report suggests that prisoner abuse by U.S. soldiers went beyond the torture and humiliation of detainees at Baghdad's Abu Ghraib (search) prison.

Unidentified members of the San Francisco-based unit "struck and pulled the hair of detainees" during interrogations during a 10-week period in spring 2003, according to the May 5 document prepared by the U.S. Army's Criminal Investigation Command.

The report also said members of the 223rd allegedly "forced into asphyxiation numerous detainees in an attempt to obtain information."

The command has "ongoing criminal investigations into detainee deaths and detainee abuse" in Iraq and Afghanistan, spokesman Chris Grey said.

One of those investigations focuses on the 223rd battalion, confirmed Denise Varner, a spokeswoman for the California National Guard who said she could not comment any further.

The 223rd battalion was attached to the Army's Third Infantry Division (search) that led the assault on Baghdad in April 2003 and patrolled the city and its surrounding areas after the collapse of Saddam Hussein's regime.

The battalion had about 100 members who interrogated detainees and cultivated sources to gather information on the whereabouts of Saddam Hussein (search), top Baath Party officials, insurgents and terrorists.

Earlier this month, several members of the 223rd told The Associated Press that they had never used or witnessed the kind of violence and humiliation captured in photographs of American soldiers abusing Iraqi detainees at Abu Ghraib.

Sgt. Ken Weichert led a team of military interrogators for about six months last year in Samarra. He said Thursday that he had no knowledge of the types of abuse detailed in the New York Times article and did not hear about the investigation until last week.

Weichert, 37, said he believes the soldier who made the allegations left Samarra on medical leave just before Weichert got there last July. When Weichert arrived in Samarra, he said he did not see any indication that the military interrogators had abused detainees.

"Never once did we experience any of those acts of abuse," Weichert said. "It did not happen under my watch. If anyone came close it, I would have fired them on the spot."