Iran and Russia will find it hard to agree any oil or gas trade deal because they are rivals in both markets, Iran's deputy oil minister for international trade said.
Iran and Russia have been discussing various ways of increasing bilateral trade, including Moscow possibly taking up to 500,000 barrels a day of Iranian oil in exchange for Russian goods that Iran needs.
Washington says such a deal would go against the terms of the interim nuclear deal between world powers and Iran.
But Ali Majedi, Iran's deputy oil minister for international affairs and trade, said Moscow and Tehran would struggle to agree such a deal.
"Many people think oil and gas is the main issue but this is very difficult because both countries are producers and exporters of oil and gas," Ali Majedi told reporters on the sidelines of a conference in Dubai.
Moscow and Tehran want to improve relations by increasing bilateral trade, which is currently very low. But striking a barter deal involving oil or gas is far harder with a major fuel exporter than with major oil importers like China, he said.
"Russia is a producer and exporter of oil, therefore this is not easy. There is no way that Iran will receive some of the oil from Russia. Maybe vice-versa, maybe. But not now," he said on the sidelines of the Middle East Petroleum and Gas Conference.
"Maybe this is one way but it's not easy and up to now no contract, no agreement, has been signed between the two countries. But the negotiation is continuing."