Russian Foreign Minister Sergey Lavrov, right, and U.S. Secretary of State Hillary Rodham Clinton speak at a news conference in Moscow Tuesday. (Ivan Sekretarev/Associated Press)

Threatening Iran with more sanctions would be counterproductive, Russia's foreign minister declared Tuesday, resisting efforts by U.S. Secretary of State Hillary Rodham Clinton to win agreement for tougher measures if Iran fails to prove its nuclear program is peaceful.

Foreign Minister Sergey Lavrov spoke as Clinton visited Moscow, her first trip since becoming America's top diplomat, in an effort to gauge Moscow's willingness to join the U.S. in imposing sanctions.

Lavrov said Russia's position is that under current conditions even the threat of sanctions against Iran would be counterproductive.

Clinton said the U.S. agreed it was important to pursue diplomacy with Iran.

"At the same time that we are very vigorously pursuing this track, we are aware that we might not be as successful as we need to be, so we have always looked at the potential of sanctions in the event we are not successful and cannot assure ourselves and others that Iran has decided not to pursue nuclear weapons," she said at a joint news conference.

Iran insists it has the right to a full domestic nuclear enrichment program and maintains it is only for peaceful purposes, such as energy production.

'Reset' relations

U.S. President Barack Obama — who visited Russia in July — has vowed to "reset" U.S.-Russia relations. On Tuesday, Clinton apologized for missing that meeting because of a broken elbow.

Clinton is to meet with Russian President Dmitry Medvedev later Tuesday.

Beyond Iran, Lavrov said U.S. and Russia negotiators have made "considerable" progress toward reaching agreement on a new strategic arms treaty. The 1991 Strategic Arms Reduction Treaty, or START, expires in December and negotiators have been racing to reach agreement on a successor.

The two diplomats also discussed possible co-operation on missile defence following Obama's decision not to proceed with Bush-administration plans to base such a system in eastern Europe.

Russia has welcomed Obama's new approach, but has said it was eager for more detailed information.

Clinton said the U.S. would be as transparent as possible.

'Deep co-operation'

"We want to ensure that every question that the Russian military or Russian government asks is answered," she said, calling missile defence "another area for deep co-operation between our countries."

Also on the agenda were Afghanistan, nuclear-armed North Korea, NATO expansion, the situation in Georgia after its conflict with Russia last year, human rights and arms control.

Iran is already under three sets of UN sanctions. Russia and China have balked at imposing new penalties on Iran, although Medvedev has hinted that the Russian position might be shifting after Tehran disclosed a previously secret uranium enrichment site near the holy city of Qom.

Medvedev said last month that while sanctions are rarely productive "in some cases they are inevitable." Lavrov stressed Tuesday the president meant that sanctions would be considered only when all political and diplomatic efforts are exhausted.

Sanctions have become a harder sell after Iran agreed to allow UN inspectors to visit the Qom site and agreed, in principle, to send most of its low-enriched uranium to Russia for reprocessing.