Iran is optimistic it can reach a deal on its disputed atomic programme with three European states, avoiding the UN Security Council where it cannot count on strong support.
Washington insists Iran's nuclear fuel is intended for warheads whereas Tehran contends it is for power stations.
France, Germany and Britain, leading negotiations on behalf of the European Union, have been encouraging Iran to drop its fuel programme in return for economic incentives.
Senior nuclear negotiator Mr Hossein Mousavian was quoted on Iranian state television today as saying the European stance was encouraging.
"The three EU countries appeared more serious in this round of negotiations compared with before and progress is being made," he said of talks that took place in Geneva this week.
"If the Europeans continue this seriously in the next two rounds, talks will continue and there is a possibility of an agreement after three months," he was quoted as saying.
Iran has said previously it will only stay committed to the EU talks if it feels progress has been made in the three months from when they began in mid-December.
As a goodwill gesture, Iran has agreed to suspend uranium enrichment, a key part of producing nuclear fuel, for as long as the talks go on. Iran is adamant it will never permanently end fuel production and is seeking to solve the nuclear impasse by promising stronger guarantees that it will never seek arms.
Mr Mousavian said details of the bargaining remained secret.
Mr Hassan Rohani, Secretary General of the Supreme National Security Council, said that if the talks with the EU trio failed, the issue would be transferred to the UN Security Council, which has the power to impose sanctions.
"But if Iran's case is referred to the council, the probability of those countries using their veto right is very low," he was quoted as saying in the Hamshahridaily.
His remarks contrasted with those of other Iranian officials who have said Tehran, which has cultivated ties with permanent members Russia and China, need not fear referral to the council.
Russia is helping build Iran's nuclear power plants and shares technology on the Islamic Republic's satellite programme.
China's booming economy takes 14 per cent of its oil imports from Iran, OPEC's second biggest producer.
But Rohani held out little hope that major powers would back Iran against Washington's wishes in the Security Council.
"The Russians, Germans and French acted against the United States over Iraq and did not let the case be discussed at the Security Council. But today, all three are trying to get close to America," he said.