"Iran plans to stop selling its oil in dollars," Ebrahim Sheibani was quoted as saying, adding that Iran had reduced its assets held in dollars to 20 percent.

The report did not give further details.

Iran said in December it would replace the dollar with the euro in foreign transactions and state-held foreign assets, in an apparent response to mounting US pressure on its banking system.

Iran is under UN sanctions over its refusal to halt sensitive nuclear work. The sanctions, targeting its nuclear and missile programmes, include a freeze on assets for people involved in these programmes.