Russia's Foreign Ministry repeated the offer yesterday, saying it would be possible for a joint Russian-Iranian project to enrich the uranium for use in Iranian reactors on Russian territory instead of in Iran.
Iranian Foreign Ministry spokesman Hamid Reza Asefi said at a news conference today that Tehran had still not received a concrete offer from Russia.
"Regarding the [Russian nuclear] plan you are talking about -- some ideas have been mentioned about it, but we have not yet received any specific proposal," he said.
But Asefi said in any case the Iranian government wanted to exercise "the right of the Islamic republic to carry out enrichment on its own soil."
Iran's nuclear program has raised concerns among many countries, particularly the U.S., which says Tehran is using the program to secretly develop nuclear weapons.
Russia has been helping Iran build nuclear power facilities and has tried to act as a mediator between Iran and countries opposed to Iran's nuclear program.