In a weekend punctuated by angry verbal exchanges between Iranian and Western leaders Tehran showed no signs of curbing its nuclear ambitions, which many outside Iran suspect is a cover for building a nuclear bomb.

On Saturday the International Atomic Energy Agency (IAEA) voted to report Iran to the UN Security Council, which has the power to impose sanctions and use force against the Iranians. To Tehran’s dismay, 27 of the 35 member states on the IAEA’s board of governors voted in favour of the move, with 5 abstentions. Iran’s only support came from Cuba, Venezuela and Syria.

The move will not come into effect until March 6, when Mohamad ElBaradei, the IAEA’s Director-General, is due to report back to the nuclear watchdog on Iran’s atomic industry. It had been hoped that the month would allow further diplomatic efforts to find a compromise solution.

Yesterday those hopes were fading fast after the Iranians were good to their word and announced a hardening of their position.

Manouchehr Mottaki, the Iranian Foreign Minister, said that Tehran was withdrawing from its commitments under the so-called “additional protocol”, signed two years ago with the IAEA, which allowed the UN’s inspectors to make snap visits to atomic sites. Iran also signalled that it would go ahead with the enrichment of uranium, which can be used to produce fuel for a civilian nuclear power industry or, in its highly enriched form, can be diverted to make fissile material suitable for an atomic warhead.

“Iran has stopped all voluntary measures that it undertook in the past two and a half to three years,” Mr Mottaki said. “We have no commitment to the additional protocol any more . . . We had two clear options. One was to decide to abandon our nuclear rights, the other to preserve our rights. We chose resistance.”

Yesterday diplomats insisted that there was still hope that a compromise could be reached in the coming weeks. On February 16 Russian and Iranian officials are due to discuss a Russian offer to carry out enrichment work on Iran’s behalf. The nuclear fuel would then be shipped to Iran for use at its nuclear power station, currently being built by Russian engineers. “Iran has still a crucial opportunity between now and the March IAEA board to comply,” Jack Straw, the Foreign Secretary, said. “Otherwise, decisions by the Security Council are almost inevitable.”

Those who have negotiated with Iranians in the past point out that they always hold out until the very end to achieve the best deal. It is hoped that pragmatists in the regime may yet prevail before the UN Security Council moves to impose punitive sanctions.

The likelihood of a climbdown by Iran seemed, however, to be more remote than ever yesterday. Saturday’s IAEA resolution demands that Iran freeze its uranium enrichment, halt the construction of a heavywater reactor that could produce plutonium, which is also fissile material, and grant the agency’s inspectors greater authority to probe its nuclear industry.

In typically defiant fashion President Mahmoud Ahmadinejad dismissed the resolution as “funny” and branded Iran’s enemies “idiots”. “Our enemies cannot do a damn thing. We do not need you at all. But you are in need of the Iranian nation,” he told a crowd in Tehran. “Issue as many resolutions like this as you want and make yourself happy. You can’t prevent the will of the Iranian nation,” he said. “In the name of the IAEA they want to visit all our nuclear facilities and learn our defence capabilities, but we won’t allow them to do this.”

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