MOSCOW — Russia could back sanctions against Iran if it fails to take a constructive stance in international talks over its nuclear program, President Dmitry Medvedev said in remarks released Saturday.

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 1,100 kilograms of low-enriched uranium -- around 70 per cent 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 UN-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 defence 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 defence 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."