In a statement released on Saturday, the military said the men had been charged with violations of the Uniform Code of Military Justice after one soldier reported that others had allegedly assaulted detainees. The nature of the assaults was not specified.

"The army's criminal investigation division immediately began an investigation into the reported incident for possible criminal conduct," the statement said.

"None of the insurgents required medical treatment for injuries related to the alleged assault. Only one of the suspected terrorists remains in custody of coalition forces at this time," the statement added.

"The unit involved has been pulled off line to complete the inquiry and retraining."

The military declined to go into details, saying specifics of the investigation or the circumstances surrounding the incident "cannot be released until all administrative and judicial actions linked to the investigation have been completed".

There have been a number of convictions of US service personnel for abuse of detainees in Iraq, most notoriously at the Abu Ghraib prison on the outskirts of Baghdad where hundreds of people are detained.