The top diplomats of Russia and Iran sought a breakthrough Wednesday on a deal that could revive the stalled nuclear talks between the Islamic state and Western powers suspicious of its weapons drive.

Foreign Minister Sergei Lavrov met his Iranian counterpart Ali Akbar Salehi to discuss the details of a "step-by-step" plan proposed by Moscow that rewards Tehran for greater transparency with a gradual easing of UN sanctions.

The second round of negotiations in Moscow came a day after Iranian President Mahmoud Ahmadinejad received Russian Security Council chief Nikolai Patrushev and pronounced his approval of the new approach.

"Iran welcomes Russia's step-by-step proposal and is ready to make suggestions to cooperate," Ahmadinejad said in comments released by the president's website.

But it is Iran's all-powerful supreme leader Ayatollah Ali Khamenei who has the final say on the country's major political decisions -- especially on foreign policy and the nuclear issue.

The Iranian foreign minister also praised Lavrov for pushing ahead with an initiative that could potentially ease the growing international isolation his country has come under in recent years for its nuclear drive.

"Your excellencies' action are a movement forwards and are good and constructive actions," Salehi told Lavrov in opening remarks.

Lavrov first presented Russia's new proposal during a July meeting in Washington with US President Barack Obama.

Previous attempts by Russia to mediate between its traditional Middle East partner and the West have been viewed with suspicion by the US administration and Washington has thus far taken a wait-and-see approach to the latest bid.

A Russian foreign ministry source told the Kommersant business daily that Lavrov's plan "is not an actual document but a series of proposals."

The Russian diplomat added that the idea has been agreed by other major Western powers and "has received their support".

But he also admitted that US officials in private conversations think that "Lavrov's plan is unlikely to succeed" and would much prefer putting additional pressure through stronger sanctions.

The Iranian negotiations involve the five permanent members of the UN Security Council plus Germany -- the so-called P5+1. The last round of talks between the Islamic republic and the group broke down in January.

Iran remains adamant that it will push ahead with its controversial nuclear enrichment activities while denying that they are a part of a secret weapons programme.

Russia for its part has heightened its criticism of Iran and now argues that it is up to the Islamic state to prove its peaceful intentions.

Lavrov said that his recent contacts with Tehran suggest a more evident readiness to listen to foreign demands.

"I have the impression that there is an understanding of the need to strengthen trust and solve the question concerning the Iranian nuclear programme," Lavrov said as he opened his talks with Salehi.