A member of Iran's team about to start a new round of negotiations with world powers in Moscow on Monday said the talks are doomed if his country's "right" to uranium enrichment is not recognised.
"If this demand isn't recognised, the negotiations are certainly headed for failure," the official said, according to state news agency IRNA, which did not identify him.
"The floor under Iran's demands in the Moscow round is the recognition of its right to uranium enrichment," the official was quoted as saying.
"If our demand on the acceptance of the right to enrichment is not recognised, we are not afraid of the talks failing," he added.
Iran wants the P5+1 group of powers -- the United States, Britain, France, Germany, Russia and China -- to discuss a five-point plan it advanced in the last round, in Baghdad last month, the official stressed.
"As long as there is no agreement on that, we don't want to talk about any future negotiating rounds," he said.
Iran has said repeatedly that it has a right to enrich uranium to fuel its nuclear programme, which it asserts is exclusively peaceful.
But the UN Security Council, whose five permanent members are leading the talks with Iran, has issued six resolutions demanding Iran halt all enrichment.
The United States has since implied that it might accept some limited and low-level enrichment activities in Iran -- but only if the Islamic republic first clears up suspicions the West has that parts of its nuclear programme is directed at gaining atomic weapons capability.
Iran has stood defiant in the face of UN and Western sanctions, forging ahead with its enrichment activities, including in a fortified bunker in Fordo, near its holy city of Qom.
Parliamentary speaker Ali Larijani was quoted by IRNA on Monday saying the Moscow talks must not be seen as so crucial to Iran.
"This matter (the talks) must not be taken to be so important that the Westerners think they can impose something on Iran," he said.