The proposal, which is backed by Washington and the European Union, involves the creation of a joint Iranian-Russian company to enrich uranium in Russia.
The plan has been put forward by Moscow in a bid to allay international concerns that Iran could manufacture highly enriched uranium on its own soil to build atomic weapons.
Iran says it only wants to enrich uranium to a low-grade, suitable for use in atomic power reactors.
Hossein Entezami, a spokesman for Iran's Supreme National Security Council, told AFP that "Iran has received the Russian proposal and is examining it", one day after a senior official acknowledged the proposal for the first time.
However, the Russian Defence Ministry on Thursday denied any conversation between Larijani and Ivanov about Iranian nuclear enrichment in Russia, with a spokesman calling such reports "false".
Change of tone
Iranian officials had previously said they would reject any plan which denied Iran the right to enrich uranium on its own
But in a sudden change of tone, a senior official said on Wednesday Tehran would "seriously and enthusiastically" study the Russian plan.
Iran says it only wants to enrich
uranium into power-plant fuel
The Iranian diplomat, speaking on Thursday to Reuters on condition of anonymity, said the agreement for talks on the proposal came during a telephone conversation between Ali Larijani, Iran's chief nuclear negotiator, and Sergei Ivanov, the Russian defence minister.
Larijani told Ivanov there were "ambiguities and problems" with the Russian plan but that "the outline of the proposal can be reviewed", the diplomat said.
Ivanov agreed to send a delegation to Tehran led by one of his deputies for further talks, the diplomat said, without specifying when they would take place.
The diplomat added that both sides had noted that their talks were unrelated to Iran's ongoing nuclear negotiations with the EU trio of Britain, Germany and France.
The Europeans are hoping the compromise can bring a breakthough in deadlocked negotiations aimed at ensuring Iran cannot produce nuclear weapons.
Talks between Iran and Britain, France and Germany resumed earlier this month, making little progress, and are to continue in January.
The US says Iran does not lack
non-nuclear sources of energy
Iran says its nuclear programme has the sole aim of making fuel for atomic reactors that would generate electricity and denies US charges it is trying to develop nuclear weapons.
Hardliners within the conservative camp have denounced the Russian proposal. Hardline lawmaker, Saeed Aboutaleb, described the Russian proposal as a "dirty trick".
The nuclear programme is regarded as a source of national pride in Iran, and any government abandoning enrichment likely would lose support.