Iran's OPEC governor Hossein Kazempour-Ardebili has fallen into a coma after suffering a brain haemorrhage, the country's oil ministry said.

"Kazempour_Ardebili is in a coma. He was hospitalised on Friday due to a severe brain haemorrhage," the ministry said in a tweet on Sunday. "May Lord's healing hand rest upon him," it said, without giving any further details.

The veteran politician was appointed governor to the Organization of the Petroleum Exporting Countries in 1985. He had also served as the Islamic republic's ambassador to Japan from 1990 to 1995. A founding member of the OPEC oil cartel, Iran sits on the world's fourth-biggest oil reserves and second-largest gas reserves.

But its economy has been battered by sanctions imposed by the United States since US President Donald Trump pulled out of the Iran nuclear deal in 2018.