A Russian envoy has made an 11th-hour bid to broker a compromise between Iran
and the West over its nuclear programme.
The move comes on Saturday, as a UN inspector was to hold a last round of talks in Tehran before the release of a report that could spark Security Council action.
Sergei Kiriyenko, Russia's atomic energy head, said his country's offer to enrich uranium on Russian soil was still on the table. He spoke after talks with Gholamreza Aghazadeh, his Iranian counterpart.
A first round of Iran-Russia nuclear talks in Moscow was wrapped up on Tuesday with Iranian officials saying they were hopeful a Russian compromise to end the crisis over the nuclear programme would bear fruit.
Russia, as a veto-wielding member of the UN Security Council with traditionally close ties to Iran, has been trying to mediate in the long-running dispute.
Aghazadeh, the head of Iran's Atomic Energy Organisation, said talks with Russia had focused on finalising the Russian-built nuclear power station at Bushehr in southern Iran, the country's first.
Aghazadeh, said: "The main issue discussed was examining the latest situation of the Bushehr plant.
"We also talked about Russia's willingness for future co-operation in developing peaceful nuclear activities."
However, ITAR-TASS agency quoted an unidentified member of the Russian delegation as saying it was highly unlikely an agreement would be reached before the end of Kiriyenko's three-day visit.
While the Russians are offering to enrich uranium outside Iran, the Islamic republic insists it will not give up its right to the process and has already started very low-level enrichment, ending a voluntary suspension.
Aghazadeh (L) said talks with
Russia focused on the Bushehr
The West is equally adamant that Iran should not master uranium enrichment as it can create both fuel for civilian reactors and, taken one step further, the explosive core of an atomic bomb. Iran denies it wants the bomb.
Kiriyenko, due to visit Bushehr on Saturday, said there was a "basis for co-operating in the domains of fuel and the construction of power stations".
Lu Guozheng, the deputy foreign minister of China - another permanent member of the Security Council - was also in Tehran on Saturday although there were no reports of a combined Russian-Chinese meeting with Iranian officials.
Olli Heinonen, a senior UN nuclear inspector, was also due in Tehran, days ahead of the planned release on Monday to International Atomic Energy Agency (IAEA) governors of a report on Iran's nuclear programme by Mohamed ElBaradei, the agency's chief.
"We also talked about Russia's willingness for future co-operation in developing peaceful nuclear activities"
Iran's Atomic Energy Organisation
Diplomats in Vienna, where the IAEA is based, said Iran had promised to answer US accusations it was doing atomic weapons work, including designing missile warheads.
Under pressure from Western countries, the IAEA board reported Iran to the UN Security Council on 4 February, over fears its nuclear programme may be a cover for atomic weapons development.
UN action suspended
However any action by the Security Council, which could include sanctions, has been suspended until the board reviews the report at a 6 March meeting in Vienna.
Uranium enrichment is seen as a red line by the US and European Union, as it is the so-called "breakout capacity" for making atomic weapons.
Iran says its nuclear programme is a peaceful effort to generate electricity and that it has a right under international law to enrich uranium.