Russia has agreed to ratchet up pressure on Iran gradually but opposes sudden and "excessive" UN sanctions in response to Tehran's refusal to curb its nuclear program, Foreign Minister Sergei Lavrov said here Wednesday.

"We agreed earlier to act on Iran gradually, in proportion to the actual situation, and we will not support excessive sanctions," Lavrov said during an appearance in the Russian parliament.

He said proposals to include a ban on foreign travel for senior Iranian officials and a freeze on international loans had been removed from new sanctions under discussion among six major powers at the United Nations in New York.

Lavrov spoke a day after the Russian ambassador to the United Nations denied US press reports that Moscow had threatened to withhold nuclear fuel for Iran's Bushehr nuclear plant if Tehran failed to meet UN demands to suspend uranium enrichment.

"I can tell you that the report is not accurate, that there has been no Russian ultimatum to Iran of any kind," the Russian ambassador to the UN, Vitaly Churkin, told reporters.

"We continue to regard the Bushehr project as something that is outside the scope" of the UN sanctions resolutions.