British diplomats, backed by America and the European Union, convinced the International Atomic Energy Agency (IAEA) to take the initiative amid growing international concern over what is feared to be the Islamic state’s covert weapons programme.

A British resolution, passed by the IAEA’s board at a meeting in Vienna, said there was an “absence of confidence” that Iran’s atomic programme was exclusively peaceful, which gave rise to questions “within the competence of the security council”.

However, the resolution did not say when Iran would be referred to the UN — watering down an earlier draft that had called for the issue to be taken up immediately. Diplomats said that this would probably give Iran at least until the IAEA board meets again in November to climb down.

America, which has long suspected Iran of trying to develop nuclear arms, said a clear signal had to be sent to Tehran. “The IAEA has called on Iran to come clean,” said Gregory Schulte, the chief American representative to the meeting.

Iran, which has denied it wants to build a bomb, immediately threatened retaliation. “Threat invokes threat,” said Javad Vaeidi, head of the Iranian delegation, without giving more details.

Before the vote, Iran indicated it might react to any attempts to impose sanctions on it by resuming enrichment of uranium at a mothballed facility in Natanz — a possible step towards the making of nuclear arms. It said it would also stop IAEA inspectors working in the country.

The threats were contained in unsigned letters shown by a member of the Iranian delegation to Mohamed ElBaradei, head of the IAEA.

The resolution was backed by 22 of the 35 members of the IAEA’s governing board, with 12 abstentions and one vote against.

In an important victory for western efforts to ratchet up the pressure on Tehran, both China and Russia, which had strongly opposed the EU’s proposed resolution, eventually abstained. Venezuela was the only country to vote against it.

Britain, France and Germany — the so-called EU3 — have tried for two years to persuade Iran that it must abandon its programme to enrich uranium fuel if it is convince the world that it is not trying to build an “Islamic bomb”.

Iran responded last year by voluntarily suspending work at its uranium conversion facility at Isfahan and its enrichment plant at Natanz. But last month it rejected an EU offer to be supplied with nuclear fuel from abroad and unilaterally restarted conversion work at Isfahan. This prompted the EU3 to join Washington, which had been long been calling for the case to be sent to the security council.

Mahmoud Ahmadinejad, the new hardline president, giving his maiden speech before the UN general assembly last weekend, accused the West of “nuclear apartheid” and declared his intention to build a civilian nuclear industry.

Iran struck an equally belligerent tone at military parades on Friday marking its 1980-88 war with Iraq. Ahmadinejad warned any enemy would find “the flame of the Iranian nation will be very destructive and fiery”.

The UN could impose sanctions if it determines Iran violated the Nuclear Nonproliferation Treaty but the draft made no mention of what measures might be taken — apparently in recognition of Russian and Chinese opposition. As members of the security council, both countries wield vetoes.

Explore World News

• Iraq News

• US & Americas News

• Europe News

• Middle East News

• Asia News

• Africa News

• Ireland News

Times Recommends

• Congo's rangers risk their lives to guard gorillas
• Pearl farming in China losing its lustre
• Axl Rose mystery as album arrives at last