PARIS - China told other world powers on Thursday that discussing broader sanctions against Iran was counterproductive, striking a blow to a Western push to rein in Tehran's nuclear program.

Chinese Foreign Minister Yang Jiechi told a conference during a visit to France that Tehran's negotiating position was evolving and he wanted to see more direct talks with Iran.

"To talk about sanctions at the moment will complicate the situation and might stand in the way of finding a diplomatic solution," Yang said.

France is among Western powers pushing for the UN Security Council to approve a fourth round of sanctions against Iran by the end of March to try to force Tehran to freeze uranium enrichment, which can have peaceful or military purposes.

Russia, like China, has extensive economic ties with Iran and has also expressed reservations at the Security Council over sanctions. But a Russian lawmaker said Thursday understanding between it and other powers on extra sanctions had increased.

Western governments fear Iran wants to produce nuclear weapons. Tehran says its atomic program is purely for peaceful purposes, but is restricting inspections of its sites by the Vienna-based UN International Atomic Energy Agency (IAEA).

In October, the IAEA drafted a plan for Iran to ship most of its enriched uranium to Russia and France for conversion into fuel for a medical research reactor to ease fears the Islamic Republic is seeking nuclear weapons from enrichment.

Iran rejected the plan but earlier this week Iranian President Mahmoud Ahmadinejad said his country was ready to send its enriched uranium abroad in exchange for more highly enriched fuel to produce medical isotopes.

Western diplomats said the shift could be a delaying tactic but Yang said it meant talks should continue.

"So, the whole thing is still evolving, we think it is very important to concentrate on the diplomatic interaction," he said. "I don't think the Iranians have totally shut the door on this proposal."

Changing conditions

In Moscow, Konstantin Kosachyov, the Kremlin-allied head of the foreign affairs committee in the lower house of parliament, showed signs of frustration with Iran's response.

"The problem is that Iran is constantly changing its conditions," Kosachyov said.

Shortly after he spoke, Russian Foreign Ministry spokesman Andrei Nesterenko urged Iran to convey its position formally to the UN nuclear agency. He said Tehran should clarify whether it was dropping its insistence on the simultaneous exchange of uranium for fuel on Iranian territory.

Iran's ambassador to Russia, Mahmoud Reza Sajadi, told Reuters that such issues were not set in stone. "As the president mentioned, it's under discussion and we are looking for a suitable formula -- not making a precondition," the ambassador said. "We are ready, open for discussion."

The United States, Britain, France, Germany, Russia and China have been trying to engage with Iran for years over its nuclear project, but Western diplomats and analysts say they have made virtually no progress.

"Ahmadinejad's statement earlier this week about accepting the swap deal gives China further reason for delay, even though Iran's position is still unclear and very certainly does not go back to the original principles of the swap deal," said Mark Fitzpatrick, senior fellow for non-proliferation at the London-based International Institute for Strategic Studies.

French Prime Minister Francois Fillon said Wednesday time was running out for a political solution to the standoff over its nuclear ambitions and Paris would press for "strong sanctions" against Iran at the United Nations.

Kosachyov said Russia's position and that of other nations had moved closer on the issue of extra sanctions.

"As regards a tougher conversation with Iran, the application of some additional sanctions of an economic character - on this question mutual understanding between Russia and its partners in the international arena has clearly increased,," he told state-owned Vesti-24 television.

US Secretary of State Hillary Clinton said last week Washington was trying to persuade Beijing it was time to get tough with Iran on its nuclear program, even though Iran is a major oil supplier to China.

Fitzpatrick said both China and Russia would seek to delay and water down any resolution on Iran, but he saw one emerging eventually. "China will not block a sanctions resolution. It may well abstain however," he said.