Iraqi officials say a mass grave containing more than 150 bodies has been uncovered to the north-east of Baghdad.
The grave, just south of Baquba in Diyala province, is believed to be three to four years old but it is unclear who is responsible for the deaths reports the BBC.
According to a military official, the bodies are those of al Qaeda insurgents who had been killed in clashes with Iraqi and American forces.
But a police official says they are the victims of insurgent groups.
The province was one of the most volatile regions in Iraq during the peak of sectarian fighting.