Russia would approve sanctions on Iran only if it saw hard evidence that Tehran's nuclear programme was not peaceful, Itar-Tass news agency quoted a foreign ministry spokesman as saying today.
The United States and some other major powers believe Iran may be building a nuclear bomb. But they say evidence that Iran is not complying with the United Nations nuclear watchdog is enough on its own to justify sanctions.
Russia - a UN Security Council veto-holder - has said it is not convinced that sanctions would persuade Iran to abandon uranium enrichment. But Moscow has not before been explicit about what evidence it would need to consider sanctions.
"We will only be able to talk about sanctions after we have concrete facts confirming that Iran is not exclusively involved in peaceful nuclear activities," Tass quoted spokesman Mikhail Kamynin as saying.
A Russian national security official said separately that sanctions did not figure on Russia's agenda at this stage.
Asked about the prospect of sanctions, Nikolai Spassky, deputy head of Russia's National Security Council said: "That question does not exist. For us at this stage it does not exist. We are discussing it," RIA news agency reported.
Mr Spassky also rejected a call made this week by a senior US State Department official for Russia to cancel the planned sale of its Tor tactical surface-to-air missile systems to Iran.