The statement echoed earlier comments by Medvedev, but contrasted sharply with the words of Prime Minister Vladimir Putin, who has warned that the threat of sanctions could thwart talks with Iran.

Medvedev said in an interview with Germany's Der Spiegel magazine that it would be better to avoid sanctions, but they can't be excluded if there is no progress in the talks. His comments were released by the Kremlin.

“If the Iranian leadership takes a less constructive stance, everything is theoretically possible,” Medvedev said, adding that he discussed the issue with President Barack Obama when they met in New York in September. Medvedev said then that sanctions are sometimes inevitable.

“I wouldn't like to see all that ending in the introduction of international sanctions, as sanctions usually is a step in a very difficult and dangerous direction,” Medvedev told Der Spiegel. “But if there is no movement forward, no one is excluding such a scenario.”

Medvedev said that Iran can implement what it claims to be a peaceful atomic energy program under international supervision. “But it must abide by the existing rules and not try to hide some facilities,” he added.

A UN-brokered plan requires Iran to send 1.2 tons (1,100 kilograms) of low-enriched uranium —around 70 percent of its stockpile — to Russia in one batch by the end of the year in order to ease international concerns the material would be used for a bomb.

Senior Iranian lawmakers on Saturday rejected any possibility of Tehran shipping uranium abroad for further enrichment, intensifying pressures on the government to reject the U.N.-backed plan altogether.

Russia has walked a fine line on Iran for years. It is one of the six powers leading efforts to ensure Iran does not develop an atomic bomb. But it has close ties with Iran, a regional power close to Russia's vulnerable southern flank, and it is building the country's first nuclear power plant.

Russia signed a contract two years ago to sell S-300 surface-to-air defense missiles to Iran, but Russian officials said no deliveries have been made yet. No reason has been given for the delay, but Israel and the United States strongly objected to Iran obtaining the long-range missiles, which would significantly boost the country's air defense capacities.

Asked whether Russia plans to sell any weapons to Iran, Medvedev gave an evasive answer.

“We will only supply weapons which are clearly defensive,” he said without elaboration. “We have no intention to supply offensive weapons.”

The Russian president also said that Russia and the United States have a good chance at signing a new nuclear arms reduction deal before year's end, but other nuclear powers must join disarmament efforts to move toward a nuclear-free world.

Medvedev told the German magazine Der Spiegel that the U.S.-Russian arms control talks have been going at a good pace. “We have every chance to agree on a new treaty, determine new (weapons) levels and control measures and sign a legally obliging document in the end of the year,” he said in remarks released by the Kremlin.

Moscow and Washington are negotiating a successor deal to the 1991 Strategic Arms Reduction Treaty that expires on Dec. 5. Efforts to slash U.S. and Russian nuclear arsenals have been a major part of President Barack Obama's push to “reset” relations with Russia, which became tense under the previous administration.

Russian and U.S. diplomats are set to launch another round of negotiations in Geneva on Monday. A Russian Foreign Ministry spokesman has voiced hope it would be conclusive.

While speaking optimistically on a new U.S.-Russian arms deal, Medvedev sounded less upbeat about the prospect of the complete abolition of nuclear weapons. President Barack Obama and Medvedev both said last April they were committed to the eventual goal of a nuclear-free world.

Medvedev told De Spiegel that other nuclear powers have been reluctant to join in disarmament efforts. “A nuclear-free world is our shared ideal for which we must aspire, but a road to that is difficult,” he said. “It takes not just the United States and Russia renouncing nuclear weapons, but other countries as well.”