Gunmen in Iraqi army uniforms shot dead an ageing Sunni tribal leader and three of his sons in their beds on Wednesday, relatives said, in the latest attack to highlight Iraq's deep sectarian rifts ahead of a December poll.
A Defence Ministry official denied Iraqi troops carried out the pre-dawn slayings in the Hurriya district of Baghdad and said the killers instead must have been terrorists in disguise.
"Iraqi army uniforms litter the streets and any terrorist can kill and tarnish our image, killing two birds with one stone," the official said.
The Hurriya attack follows the discovery last week of more than 170 malnourished and beaten prisoners, many of them Sunni Arabs, locked in a bunker belonging to the Shi'ite-dominated Interior Ministry. Together, the incidents have ratcheted up fears Iraq is heading for civil war.
An Interior Ministry official said 40 men wearing army uniforms had come to the victims' house in the night. Relatives said Kathim Sirheed Ali, the 70-year-old head of the Batta tribe, and his three sons were shot as they were sleeping.
One victim was holding his daughter. "The gunmen told the girl to move then shot the father," said a relative. Television footage showed the men lying dead in their bedding with bullet casings littering the floor. Wailing women in black veils stood by the bodies.
Sunni Muslim leaders accuse the Interior Ministry of sanctioning death squads run by Shi'ite Muslim militias which attack Sunnis. The government denies the claims.
Thair Kathim Sirheed said soldiers had killed his father and three brothers, two of whom had worked as policemen.