Tony Blair today said that he remained hopeful of a diplomatic solution to the deadlock over Iran's nuclear programme, as efforts began to play down public divisions between world powers.

A spokesman for the Prime Minister said that the international community was united in its condemnation of Tehran for breaking the seals on its nuclear plants, and was working towards an acceptable solution. He said that the Islamic republic was slowly but surely becoming more isolated, despite the split in opinion abroad.

Germany, France and the UK - who comprise the E3 which has been in negotiations with the Middle Eastern country for two years - have voted to convene an emergency board meeting of the International Atomic Energy Commission on February 2, the first step in a referral to the UN Security Council and possible sanctions.

However, Russia and China, which both have major trade and energy links with Iran, today appeared to undermine the threat. Both countries wield a veto as permanent members of the Council and hinted that they could not support such measures.

The extent of the split emerged today as the various world leaders gave their pronouncements following a seven-hour meeting in London yesterday.

Sergei Lavrov, Russia's Foreign Minister, said: "Sanctions are in no way the best, or the only, way to solve the problem." Mr Lavrov referred to the ongoing instability in Iraq as an example of how international sanctions could fail to rein in a rogue state.

Russia has a $1 billion contract with Iran to build its first civil nuclear reactor and is also reluctant to risk its relations with the republic, which wields influence in the turbulent Caucasus.

A spokesman for the Chinese Government said that punitive measures would "complicate" the issue. China obtains 12 per cent of its oil from Iran.

The French, German and British Governments were today engaged in a diplomatic scramble to restore a semblence of unity among the major powers. Philippe Douste-Blazy, the French Foreign Minister, said that Russia's concerns were "very close" to those of Europe. He will meet President Vladimir Putin in Moscow for further talks tomorrow.

He said that he was convinced that Iran's claimed civil nuclear programme was cover for the development of atomic weapons. He said: "There is no civil nuclear program that could justify these dangerous nuclear activities."

Gernot Erler, Germany’s deputy foreign minister, warned: "If the international community does not act together here, there is absolutely no chance of exerting influence on Iranian policies."

A spokesman for Mr Blair said that he hoped a "gradual, sustained build-up" of pressure on the Iranian Government would force it back to the negotiating table without the need to secure international backing for economic or cultural sanctions.

"You do this step by step. Iran is in a more isolated position today than it was last week. What we should do is harness as much international support as possible behind a slowly increasing process of putting pressure on. That’s what we are trying to do."

He dismissed as "vacuous" an apparent offer by Tehran to resume talks scheduled for tomorrow, unless research into the uranium enrichment cycle is suspended. Enriched uranium can be fuel for civilian nuclear reactors, but in a highly enriched form also the raw material for a bomb.

In a further twist, it emerged this evening that Mohamed ElBaradei, the IAEA chief, had held a meeting in secret with Ali Larijani, Iran’s chief negotiator, on Sunday. A source said that Mr Larijani had been attempting to "foil" the calls for the emergency board meeting.

Russia has offered to let Iran enrich uranium in a joint venture on Russian territory, allowing it access to a supply of fuel for nuclear power stations without stockpiling material for nuclear warheads. Iran has previously rejected the offer but now appeared to be reconsidering it, in what critics have described as a ploy to gain extra time.

Iran appeared to sound another conciliatory note in the dispute by offering to return to the negotiating table in a letter to the E3 in which it emphasised willingness to "remove existing ambiguities regarding its peaceful nuclear programme through talks and negotiations". The letter, written by Javad Vaeedi, deputy head of Iran’s Supreme National Security Council, was designed to show that "despite the London meeting, Iran is determined to continue talks and to find a solution through talks."

As the European members struggled to find common ground, Colin Powell, the former US Secretary of State, gave a series of interviews in which he expressed America's "great concern". The US has not ruled out military action as a final option to delay Iran's nuclear development.

"We cannot afford another two years chatting back and forth between the international community," Mr Powell told the BBC. "It took two years to go from thinking about sending this to the Security Council and we have not got there yet.

"We would have been in a better position if it had been referred two or three years ago. The international community was not ready to do it - but they are now."

The ongoing uncertainty, combined with guerilla attacks on Western oil depots in Nigeria, forced to price of oil above the $65-a-barrel, their highest levels in three months.

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