A senior U.S. official says the soldier accused in the killing of 16 Afghan civilians is Army Staff Sgt. Robert Bales.

The official spoke on condition of anonymity because of the sensitivity of the investigation into an incident that has roiled relations with Afghanistan.

American officials had said previously that the suspect was a 38-year-old staff sergeant and that he had spent 11 years in the Army. But they had refused to release his name, saying it is military policy to identify a suspect only after he has been charged with an offence.

Bales has not yet been charged. He was being flown Friday from Kuwait to a military detention centre at Fort Leavenworth, Kansas.