Iran, OPEC's second-largest producer, has completely stopped conducting all its oil transactions in U.S. dollars, a top Oil Ministry official said.
Iran has dramatically reduced dependence on the dollar over the past year in the face of increasing U.S. pressure on its financial system and the fall in the value of the U.S. currency.
Oil is priced in dollars on the world market and the currency's depreciation has concerned producers because it has contributed to rising crude oil prices and eroded the value of their dollar reserves.
Iran has already said it was shifting its oil sales out of the dollar into other currencies.