Iran has denied reports it had blocked an oil shipment to Greece in retaliation for the EU phasing in a ban on its key export
The Iranian ISNA news agency quoted the head of Iranian Oil Terminals Co. as saying there had been no change in Iran's oil shipment to Greece or any other country.
Earlier, Iran's semi-official Fars news agency said Tehran had refused shipment of 500,000 barrels of oil destined for Greek refiner Hellenic Petroleum. A Hellenic official had denied this.
The European Union decided in January to stop importing Iranian crude as of 1 July, in the latest in a series of international sanctions aimed at forcing Tehran to halt its sensitive nuclear work, as demanded by the UN Security Council.
Iran stopped selling crude to British and French companies last week after the oil minister said Tehran would cut oil exports to "some" European countries.
Brent crude surged to over $US125 a barrel on Friday amid fears of an escalation of tensions after the UN nuclear agency issued a report showing Tehran had increased its most sensitive nuclear work.
The West says Iran's the nuclear programme is part of a weapons programme, a charge Tehran denies.
