Staff Sgt Robert Bales.

The lawyer defending the US soldier accused of murdering 17 Afghan civilians said on Friday that US authorities are blocking his ability to investigate the incident.

John Henry Browne, who is defending Staff Sergeant Robert Bales, said US forces in Afghanistan have blocked his team from interviewing injured civilians at a hospital in Kandahar, and are allowing other potential witnesses to scatter, making it difficult to track them down.

Bales was formally charged last week with 17 counts of murder for killing eight adults and nine children in a pre-dawn shooting rampage in southern Afghanistan on March 11, that further eroded US-Afghan relations already frayed by a decade of war. - Reuters