UNITED NATIONS - Russia's foreign minister made clear ahead of high-level talks Friday on Iran's nuclear program that Moscow wants to see a UN  agency report on Tehran's past suspicious nuclear work before considering new sanctions.

The Russian official, Sergey Lavrov, and Secretary of State Condoleezza Rice exchanged sharp words at a luncheon Wednesday on the subject. Rice pushed for tough new sanctions to pressure Iran to suspend uranium enrichment, and Lavrov said Moscow wanted to give nuclear inspectors time to do their job, according to the Russian minister and U.S. and European officials present.

Two UN  resolutions imposing sanctions on Iran have failed to persuade it to suspend uranium enrichment. Tehran insists its program is aimed at producing energy for civilian use but the U.S., its European allies and many others fear the program's real goal is nuclear weapons.

In a Tuesday address at the UN  General Assembly, Iranian President Mahmoud Ahmadinejad said the nuclear issue is "closed" and vowed to defy any UN  Security Council move for more sanctions.

On Thursday, French Foreign Minister Bernard Kouchner said that China as well as Russia refuses to discuss possible new sanctions against Iran until the International Atomic Energy Agency reports on Tehran past activities at the end of the year.

"I think that it would be very difficult to convince the Russians and the Chinese before," he said. "We'll do our best to convince them, but honestly, the position was difficult to tackle."

The various ministers will have another chance to debate at a meeting Friday morning of the six key international players trying to negotiate with Iran. Besides Russia and the U.S., the Chinese, British, French and German ministers are also expected to attend.

IAEA chief Mohamed ElBaradei and Iranian officials agreed in July that Tehran would answer questions from agency experts by December on more than two decades of nuclear activity -- most of it secret until revealed more than four years ago. IAEA technical officials returned to Tehran this week to start probing outstanding questions, some with possible weapons applications.

Lavrov told reporters Thursday night that the IAEA's progress with Iran "is obvious."

Security Council measures must be proportionate "and commensurate with what Iran is actually doing -- and as long as Iran is doing something which satisfies part of the demands of the Security Council, I believe we have to caliber our action in the Security Council and elsewhere," he said.

Lavrov's comments to ITAR-TASS and RIA-Novosti earlier Thursday were stronger.

"Interference by means of any sanctions would undermine the International Atomic Energy Agency's efforts," Lavrov was quoted as saying. "The UN  Security Council measures on Iran should be balanced and respond to the steps taken by Tehran itself that obliged to answer all questions."

Rice and her top aides want to capitalize on international frustration with Ahmadinejad for his recent remarks. But Lavrov said the U.S. wanted to ignore the IAEA -- as it has in the past -- but "we want to rely on IAEA expertise."

The U.S. ambassador to the UN , Zalmay Khalilzad, on Thursday said the agreement with the IAEA "cannot be used as a shield to protect Iran from its violation, lack of cooperation, lack of implementation of the demands of the Security Council" on the nuclear issue.

Khalilzad said that Iran's ability to enrich uranium to a level usable for weapons is a "threat to international security and stability. It is one of the most important, perhaps one of the defining issues of our time."

A united diplomatic front, he said, increases the chances that diplomacy will succeed. "Those who will not cooperate on the diplomacy of this, with regard to pressure on Iran, sanctions on Iran, bear some responsibility should diplomacy, God forbid, fail."