Russia said on Friday Iran must cooperate more actively with the U.N. nuclear agency to convince the world its nuclear program is peaceful, and gave fresh signals the Kremlin may back sanctions.

The International Atomic Energy Agency (IAEA) suggested on Thursday for the first time that Iran was actively pursuing a nuclear weapons capability now, rather than merely having done so in the past.

Supreme Leader Ayatollah Ali Khamenei on Friday repeated Iran's insistence that suspicions about its nuclear program were baseless. But the U.S.-led campaign for more sanctions against Tehran appeared to be gaining ground.

Tehran must be more active in its cooperation with the IAEA and widen it, Russian Foreign Ministry spokesman Andrei Nesterenko was quoted as saying at a briefing in Moscow.

The comments reinforced indications that Moscow's patience with Tehran is wearing thin, as the United States leads a push for the U.N. Security Council to impose a fourth round of sanctions.

Russia hinted that talks on a resolution could start soon.

No work is in progress at the U.N. Security Council in New York today to prepare a possible sanctions-based resolution on Iran. However, given the current circumstances, we cannot fully rule out the possibility of starting this work, Interfax quoted Foreign Ministry spokesman Andrei Nesterenko as saying.

SUSPICIONS

Nesterenko said Tehran should provide information to dispel suspicions about the character of its nuclear program, Russian news agencies reported.

The international community needs to know for certain that it is peaceful, he said.

Germany, one of the six powers negotiating with Iran on the nuclear issue, added its voice to the pressure.

The persistent defiance ... of United Nations resolutions and Tehran's continuation of a dangerous nuclear policy are forcing the international community to pursue further comprehensive sanctions in New York against the regime in Tehran, government spokesman Ulrich Wilhelm said on Friday.

The U.N. nuclear watchdog said on Thursday it feared Iran may be working now to develop a nuclear-armed missile, and Washington warned Tehran of the consequences of ignoring international demands.

The IAEA on Thursday seemed to be cautiously going public with concerns arising from a classified analysis which concludes that Iran already has explosives expertise relevant to a workable nuclear weapon.

The report also confirmed Iran had produced its first small batch of uranium enriched to a higher purity and had set aside most of its low-enriched uranium stockpile for this purpose, although this seemed far in excess of civilian needs.

The developments will intensify pressure on Iran to prove it is not covertly bent on weaponizing enrichment by allowing unfettered access for IAEA inspectors and investigators, something it rejects in protest at U.N. sanctions.

The West's accusations are baseless because our religious beliefs bar us from using such weapons, Khamenei was quoted as saying by Iranian media. We do not believe in atomic weapons and are not seeking that.