Russia and the US have pledged to work together to ensure Iran's nuclear programme is for peaceful purposes.

After talks with her counterpart Sergei Lavrov in Moscow, US Secretary of State Hillary Clinton praised Russia for its "extremely co-operative" work.

Mrs Clinton said Iran's programme was of "serious concern", but the US was not seeking further sanctions for now.

Mr Lavrov said Russia was "very reserved" about such a move. Iran says it is not developing nuclear weapons.

But it recently revealed it had a second uranium plant.

Mrs Clinton, in Moscow at the end of a five-day European tour, told a joint news conference with Mr Lavrov that Russia had "been extremely co-operative in the work that we have done together" on Iran.

Iran on defensive over secret site UN sanctions against Iran Iran and the nuclear issue

The secretary of state said the US was not seeking further sanctions pending talks between big powers and Iran - but she added that it could do so "in the absence of significant progress and assurance that Iran is not pursuing nuclear weapons".

Mr Lavrov said neither country had asked the other for anything in dealing with Iran, but that "our positions coincide".

"Threats of sanctions and threats of pressure in the current situation are, in our opinion, counterproductive," he told the news conference.

The BBC's Rupert Wingfled-Hayes in Moscow says Mrs Clinton was looking for a solid commitment from Mr Lavrov, but did not get one.

Both Mr Lavrov and Mrs Clinton also said there had been considerable progress in talks on a new treaty to reduce the two countries' nuclear arsenals.

The US secretary of state is due to meet President Dmitry Medvedev at his private residence outside Moscow later.

No quid pro quo

President Barack Obama, who met Mr Medvedev in July, has pledged to reset relations with Russia.

The US wants Russia to support the idea of further sanctions on Iran

A month ago, following the revelations about Iran's second uranium enrichment facility, the Russian president said his government might ultimately accept further sanctions as inevitable.

Since then, Mr Obama has met a key Russian demand to scrap plans to deploy interceptor missiles in Poland and a radar station in the Czech Republic as part of a US missile defence system in Europe.

The US administration insisted it did not expect concessions in return.

But US officials have called on Russia to support, or at least not oppose, the idea of the UN Security Council imposing tougher sanctions on Iran if it fails to live up to its international obligations.

The council wants Iran to end uranium enrichment and has approved three rounds of sanctions - including bans on Iran's arms exports and all trade in nuclear material.

During her visit, Mrs Clinton will not meet Russia's powerful Prime Minister, Vladimir Putin. He is in China for talks focusing on trade, but also expected to raise the nuclear programmes of Iran and North Korea.

Correspondents say that if Russia and China reject new sanctions on Iran, a coalition of countries, including the EU, might take action themselves.

There are reports that this could cover stopping sales of refined oil products to Tehran.