MOSCOW, Feb. 21 (Xinhuanet) --  Russia urged Iran to cooperate fully with the International Atomic Energy Agency (IAEA) on Tuesday as the two countries wrapped up two days of talks, described by an Iranian top negotiator as "constructive and positive," on Moscow's uranium enrichment proposal.

    "There was a serious exchange of opinions about the settlement of tensions over the Iranian nuclear program and Russia's proposalto set up a joint venture on its territory for supplying enriched uranium for Iran's nuclear energy program," the Russian Foreign Ministry said in a statement issued after the talks.

    Russia underlined the need for a comprehensive cooperation between Iran and the IAEA, which will clarify the remaining questions about Iran's earlier nuclear activities and restore confidence in its nuclear program, the ministry said.

    Iran removed UN seals at its nuclear research sites and resumedresearch on uranium enrichment in January, prompting the European Union (EU) to scrap talks. Tehran, however, said its nuclear work is merely designed to meet its energy needs.

    Earlier in the month, Britain, France and Germany, which have held on-and-off talks on behalf of the EU with Tehran for more than two years, pushed through an IAEA resolution to report Iran's nuclear issue to the United Nations Security Council.

    Western countries have backed Moscow's compromise plan, saying it could help allay concerns over Iran's potential production of weapon-grade nuclear materials.

    Uranium enriched at low levels can fuel nuclear reactors, but it can be used for nuclear bombs if highly enriched.

    The Russian plan is seen as a crucial attempt to resolve the dispute over Iran's nuclear program before the March 6 IAEA meeting, which reports say could start a process leading to UN punishment against Iran.

    Speaking on Iran's state television before leaving Moscow for home on Tuesday, Ali Hosseinitash, deputy secretary of Iran's Supreme National Security Council who led the Iranian delegation, termed the talks as "positive and constructive."

    Hosseinitash said the two sides "reached a rudimental agreementon principles of a common formula and will continue negotiations to further the agreement."

    He said certain elements of the negotiations gave hope that an agreement may be reached, the Interfax news agency reported.

    The negotiations covered not only the Russian proposal but alsopriority issues for Tehran, Hosseinitash said.

    Russian officials, however, sounded less optimistic.

    Russian Foreign Minister Sergei Lavrov, quoted by the Itar-Tassnews agency, said he "would be cautious about using the terms 'failure' or 'setback' to describe the results of the talks before they end."

    Before the talks started, Lavrov expressed cautious optimism, saying Russia had "reserved expectations" over the negotiations.

    With no clear sign of a breakthrough, Russia and Iran are set to be engage in more talks later this week. The head of the Russian Federal Atomic Energy Agency, Sergei Kiriyenko, will travel to Iran on Thursday.

    "Russia will do its best to offer Iran a possible peaceful way out of the situation," Kiriyenko said.

    The United States accuses Iran of secretly developing nuclear weapons and the EU also holds that Iran's full mastery of nuclear fuel cycle technology would possibly lead to military usage.

    Iran, however, rejects the allegation as politically motivated,

    Insisting that its nuclear program is fully peaceful and aimed at meeting rising domestic demand for electricity. Enditem