A military jury has acquitted a US marine sergeant on charges of murdering an unarmed detainee during battle in Fallujah, Iraq.

The jury at Camp Pendleton, California, also acquitted Sergeant Ryan Weemer today of dereliction of duty in the November 2004 death.

The panel of eight marines who served in Iraq or Afghanistan returned the verdict after more than four hours of deliberations.

The marine from Illinois could have faced a maximum sentence of life in prison and dishonourable discharge if convicted of murder. The maximum sentence for dereliction is six months in prison and a bad conduct discharge.

In closing arguments yesterday, a defence attorney said the 26-year-old Weemer acted in self-defence. A prosecutor recounted that Weemer said in recorded interviews that he shot the man and told a squad mate that he would have to live with that for the rest of his life.