A senior Iranian official said the country's military had conducted air strikes against Islamic State jihadists in Iraq, in an interview with British newspaper The Guardian.

Deputy foreign minister Ebrahim Rahimpour told the paper Iran conducted strikes for "the defence of the interests of our friends in Iraq", who he defined as the Baghdad government and the Kurdish autonomous region in northern Iraq, who are both fighting IS.

"In this matter, we did not have any coordination with the Americans. We have coordinated only with the Iraqi government," the newspaper quoted Rahimpour as saying.

"In general, every military operation to help the Iraqi government is according to their requests."

It would be the first official confirmation of air strikes by Tehran since US officials said earlier this week the Iranian air force carried out attacks in Iraq.

Iran at the time refused to confirm it had taken such action.

Air strikes would be politically sensitive as Washington and Tehran are historic enemies despite finding themselves on the same side against IS.

Iraq's prime minister Haider al-Abadi has said he had no knowledge of any Iranian air strikes.

Rahimpour said Iran would intervene to prevent Iraq deteriorating like its neighbour Syria, torn apart by a civil war which has killed nearly 200,000 people and displaced more than half its population.

"We will not allow conditions in Iraq to descend to the level of Syria, which has been created by foreign players," Rahimpour told The Guardian.

"And certainly our assistance (to Iraq) is stronger than our assistance to Syria, because they are nearer to us.

Iran has consistently denied having troops in Iraq, and was not invited to join a US-led military coalition against IS extremists, who have carved out a vast region of control in the country and neighbouring Syria.