They were speaking a day after foreign ministers from the United States, France, Britain, Germany, Russia and China agreed in Paris to take Tehran back before the UN Security Council for refusing to suspend its uranium enrichment programme, as demanded by the International Atomic Energy Agency (IAEA).

In an agreed statement the six also held out for the first time the threat of economic sanctions if the Islamic government refuses to heed a new call for compliance. The move was seen as highly significant because till now Russia and China have opposed talk of sanctions.

But specialists consulted by AFP agreed that the display of unity was largely influenced by this weekend's G8 summit in Saint Petersburg, which the Russian hosts want to seal with diplomatic gains of their own.

"Putin's Russia wants to present itself as a responsible power," said Didier Billion of the Paris-based Institute for International and Strategic Relations (IRIS).

According to Evgeni Volk of Moscow's Hermitage Foundation, "The Kremlin was ready to make concessions because it wants results in its bid to join the World Trade Organistion (WTO)."

"We cannot rule out Russia changing its position again once the summit is over, but on Wednesday it had no other option," said Alexei Malachenko of the Carnegie Foundation in Moscow.

The six powers agreed on a two-step process. A first Security Council reslution next week will restate Tehran's obligation to suspend its enrichment programme and set a deadline -- as yet undecided -- for a response.

In the meantime a second resolution will be prepared which would put into effect a graduated series of economic sanctions should Iran once again say no.

Diplomats said there was unanimous agreement at Wednesday's meeting after the EU's foreign policy chief Javier Solana reported no sign of a positive response from Iran to a package of incentives that was offered at the start of June.

However analysts said that despite signing up to the new steps, Russia and China remain very wary of sanctions.

"Right now (sanctions) are a subject of speculation and a hypothetical question," Russian Foreign Minister Sergei Lavrov told journalists on the plane bringing him back to Moscow.

Quoted by the Ria Novosti agency, he said that "sanctions should not be an instrument of punishment, but a way of getting Iran to cooperate fully with the IAEA."

"Russia and China are interested in putting up the pressure on Iran, but that does not mean they will agree to start applying sanctions," said Johannes Reissner of the Political Science Foundation in Berlin.

"There is a real danger that we will end up with a half measure -- sanctions that have little effect and allow the Iranians to continue with their programme of enrichment," warned Francois Gere of the French Institute for Strategic Analysis (IFAS).

US and European diplomats are persuaded that Iran is spinning out its contacts with the outside powers in order to buy time for the development of an atomic weapon.

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