The official, speaking on condition he not be named, told AFP that an Iranian delegation led by Ali Hosseini-Tash "will be in Moscow tomorrow for talks with the Russian security council" on a Russian plan backed by the West for defusing tensions over the Iranian programme.
Word of the fresh negotiations came a day after Iran announced it had reached an agreement in principle with Russia on a plan under which the two countries would set up a joint venture on Russian territory for enrichment of uranium to be used in Iran's first nuclear power station.
Russian officials quickly poured cold water on that announcement however, saying there was still much work to be done to reach an agreement and little time left to do it ahead of March 6 when the UN nuclear watchdog International Atomic Energy Agency (IAEA) is set to decide whether to refer Iran to the UN Security Council.
Hours before the new Moscow talks were announced, Hosseini-Tash said that Iran had "predicted and studied the consequences of any possible Security Council decision" and added: "There is no reason for Iran to retreat."
"Any possible Security Council resolution against Iran's peaceful nuclear activities will not have any legal or rational foundations," Hosseini-Tash was quoted as saying by state television.
"It is not the last loop in the chain of decisions, especially when the US and the West are not sure of an agreement among Security Council members."
Russian Foreign Minister Sergei Lavrov however struck an equally uncompromising tone at about the same time, demanding that Tehran reinstate a moratorium on uranium enrichment until all questions about its nuclear programme had been answered.
"The Russian proposal to create a joint venture for the enrichment of uranium in Russia is part of a general effort to remove concerns on the Iranian nuclear programme," Lavrov told journalists.
"We are convinced that, among other components of this effort, a moratorium on enrichment of uranium in Iran is required until all issues have been clarified by the experts" of the IAEA, he added.
Lavrov's comments offered one of the clearest indications to date that Russia was in line with the European Union and the United States in diplomatic efforts to persuade Iran to compromise in granting a measure of international control over the most sensitive aspects of its nuclear programme.
Russia is building Iran's first nuclear power station but it shares worries of the United States and the European Union that Iran is using its civilian nuclear power programme to hide development of atomic weapons.