Baghdad: US and Iraqi forces have killed the leader of the self-styled Islamic State in Iraq, an Al Qaida-led militant group, Iraq's deputy interior minister told Reuters on Thursday.

Hussein Kamal said Abu Omar al-Baghdadi had been killed in a battle north of Baghdad. He declined to say when but he said authorities had Baghdadi's body.

US military spokesman Lieutenant-Colonel Christopher Garver declined to comment but said a news conference would be held later on Thursday to announce the "success" of an operation against Al Qaida.

He stressed that the topic would not be Abu Ayyub al-Masri, the leader of Al Qaida in Iraq.

Iraqi officials had said Masri was killed in a fight between insurgents north of Baghdad this week. The US military has been unable to confirm those reports and no body has been found.

The Islamic State in Iraq, a body set up by Al Qaida's Iraq wing and other Sunni Arab militant groups in October, has claimed responsibility for a string of attacks, including mass kidnappings, bombings and the downing of US helicopters.