"The US has not achieved its goal in the region despite all its efforts, active cooperation between Iran and Russia on regional issues within a defined framework can hinder the US ambitious and unilateral plans," Iran's Supreme Leader Ayatollah Seyed Ali Khamenei was quoted as saying, in a meeting with visiting Russian National Security Council Secretary Igor Ivanov.

The leader also stressed Tehran welcomed development of relations with Russia in all grounds, adding that the capacity for expansion of ties between the two sides is higher than the present level.

Referring to the abundant gas reserves the two countries own, Khamenei suggested that both sides establish an organization of gas exporting countries similar to OPEC (Organization of Petroleum Exporting Countries) through mutual cooperation.

For his part, Ivanov submitted the Iranian leader a letter from Russian President Vladimir Putin, stressing the firm determination of Moscow to continue its cooperation with Tehran in all areas.

Ivanov arrived in Tehran Sunday morning for talks on Iran's disputed nuclear program. Besides meeting with Khamenei, he also held talks with Iranian President Mahmoud Ahmadinejad, Foreign Minister Manouchehr Mottaki and Supreme National Security Council Secretary and chief nuclear negotiator Ali Larijani.

Diplomatic sources said that Ivanov's visit is "crucially important" and Iran and Russia are now endeavoring to work out a new formula for the nuclear standoff.

Mottaki has said on Saturday that Tehran would welcome a "comprehensive formula" for solving the disputes over its nuclear program.

The UN Security Council passed Resolution 1737 on Dec. 23, 2006,calling on Tehran to suspend its enrichment activities and imposing sanctions on Iran's nuclear and missile programs.

Iranian officials have rejected the resolution as an "illegal measure" and vowed to continue the country's nuclear program.