A senior Russian official, National Security Council secretary Nikolai Patrushev, arrived on Monday for talks with Iranian officials on the country's nuclear programme, state news agency IRNA reported.
Patrushev is set to hold two meetings with his Iranian counterpart Saeed Jalili and also to meet other officials, including President Mahmoud Ahmadinejad, during a two-day stay.
Moscow is seeking to revive nuclear negotiations between Iran and major world powers known as the P5+1, the five UN Security Council permanent members plus Germany.
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In mid-July, Russian Foreign Minister Sergei Lavrov proposed a new "step-by-step" approach to restart talks on the nuclear issue.
In response to a positive move by Iran, the major powers would then have to start reducing international economic sanctions against Tehran.
As a follow-up to Patrushev's visit, Iranian Foreign Minister Ali Akbar Salehi is to travel to Moscow this week to continue negotiations with Russia.
Tehran has been hit by four rounds of UN sanctions over its programme of uranium enrichment, which Western powers suspect has a military dimension, despite Tehran's repeated denials.
The United States and European Union have also imposed their own unilateral sanctions on Iranian banks, posing risks for foreign companies which deal with them.