The US military reported on Saturday a clash between Iraqi army units that killed one Iraqi soldier, raising questions over the new, US-trained force's cohesion in the face of ethnic and sectarian rivalries.
But the Iraqi Defence Ministry denied all knowledge of such an incident and Iraqi army and police officers in the area gave a different account of Friday's events, describing violence between a mainly Kurdish army unit and local, Arab civilians.
The US military said its troops helped end a stand-off at Balad, 40 km (25 miles) north of Baghdad, between two Iraqi units, one of which had earlier been ambushed by rebels.
But a spokesman declined to say whether the US soldiers actually witnessed Iraqi troops killing a fellow soldier and referred inquiries to the media office of the Iraqi Defence Ministry. There, an official said he knew of no such case. Elsewhere in Iraq on Saturday, in the second city of Basra and the town of Hilla south of Baghdad, there were new signs of faction-fighting over control of mainly Shia police forces.