A senior Iranian delegation met with Atomic Energy Minister Alexander Rumyantsev in a bid to negotiate a special protocol agreement that would ensure that all fuel provided for the plant by Moscow was returned to Russia.
Russia is completing the Bushehr reactor in southern Iran but has said it will not deliver any fuel until Iran has agreed to return all spent fuel.
It has since hinted that Bushehr may not become operational until 2005 at the earliest as Iran drags its feet over signing the protocol and pursues its own uranium enrichment program -- which it has pledged to abandon.
Western nations fear that Iran wants to keep the fuel and use some of the material to develop nuclear weapons.
Russian news reports had said on the eve of the visit that the two sides might announce Wednesday when the protocol agreement would be officially signed.
But a Russian atomic energy statement issued after the meeting said only that the two sides had "discussed" the protocol agreement and that Rumyantsev had agreed to visit Iran in January.
It added that the two sides had agreed to create a working group to see whether Russia and Iran can cooperate on the construction of a second reactor at Bushehr in the future.