Russia on Tuesday dismissed new U.S. sanctions targeting Iran's financial and energy sectors as unacceptable and said they would damage any chances of renewing negotiations with Tehran over its nuclear programme.

A sharply worded Russian statement underscored Moscow's longstanding opposition to sanctions beyond those endorsed by the United Nations Security Council, where Russia holds veto power as a permanent member. The Council has passed four packages of limited sanctions against Iran since 2006.

We again underline that the Russian Federation considers such extraterritorial measures unacceptable and contradictory to international law, Foreign Ministry spokesman Alexander Lukashevich said in the statement.

It indicated that despite big powers having united to push through a U.N. nuclear agency board resolution last week that expressed increasing concern about Iran's nuclear programme, Russia continues to differ sharply with the West on how to win Tehran's cooperation.

Such practices ... seriously complicate efforts for constructive dialogue with Tehran, Lukashevich said.

The United States, which fears Tehran's nuclear programme is secretly geared to developing atomic weapons, named Iran on Monday as an area of primary money laundering concern in a step designed to dissuade non-U.S. banks from dealing with it.

It also blacklisted 11 entities suspected of assisting Iran's nuclear activity, which Tehran says is meant for peaceful purposes including power generation, and expanded sanctions to target companies that aid its oil and petrochemical industries.

Britain and Canada also announced new sanctions against Iran's energy and financial sectors while France proposed measures including freezing the assets of Iran's central bank and suspending purchases of oil.

FEWER CONCERNS IN MOSCOW THAN WEST

Russia has significant commercial ties with Iran and built a nuclear power plant, the Islamic Republic's first, that was switched on this year.

Analysts say Moscow see less risk than the West of Iran acquiring nuclear weapons in the foreseeable future, and uses its ties with Tehran as a lever in relations with the United States, its former Cold War foe.

Russia has approved four sets of Security Council sanctions over Iran's nuclear programme, most recently in 2010, when President Dmitry Medvedev also pleased Washington by scrapping a contract to sell Tehran ground-to-air missiles.

Those moves came at a time of improving relations between Russia and the United States, after President Barack Obama downsized a European missile defence plan that Russia opposed and signed a nuclear arms limitation treaty with Medvedev.

Now, however, with talks on missile defence cooperation with Washington at an impasse, and the possibility that a Republican critic of Russia could be elected U.S. president in 2012, Moscow appears to see little gain from supporting new Iran sanctions.

Prime Minister Vladimir Putin, who plans to return to Russia's presidency in a March election, has expressed less concern over Iran's nuclear ambitions than Medvedev, the protege he ushered into the Kremlin in 2008.

Russia has underlined its opposition to further sanctions and is calling instead for a step-by-step process under which existing sanctions would be eased in return for actions by Tehran to dispel international concerns.

Western powers have not warmed to that idea, given that previous talks with Iran failed even to agree an agenda, with Iran loath to negotiate any aspect of its nuclear programme.

Moscow says additional sanctions are hurting the chances of reviving talks between Iran and six global powers -- Russia, China, the United States, Britain, France and Germany.

Strengthening sanctions pressure, which for some of our partners is becoming practically an end in itself, will not promote increased readiness on Iran's part to sit down at the negotiating table, Lukashevich said.

(Writing by Steve Gutterman; Editing by Mark Heinrich)