At the same time, the hawkish envoy said he hoped diplomatic pressure would prevent Tehran from achieving its alleged nuclear ambitions.

Speaking to the BBC while on a trip to London, Bolton said: "I think that the Iranians have been pursuing a nuclear weapons programme for up to 18 years.

"They have engaged in concealment and deception and they've engaged in threats before."

Tehran insists that its nuclear programmes are designed to generate energy purely for civil purposes. But Washington has long suspected that the oil and gas rich country is trying, covertly, to develop nuclear weapons.

Bolton said: "The real issue is whether an international community is going to accept an Iran that violates its treaty commitments under the non-proliferation treaty, that lies about its programme and is determined to get nuclear weapons deliverable on ballistic missiles that it can then use to intimidate not only its own region but possibly to supply to terrorists."

He dismissed the suggestion that the United States, the United Nations or any other body was powerless to prevent Iran from building a nuclear arsenal.

Earlier in Paris, US Secretary of State Condoleezza Rice reiterated a warning to Iran to restart negotiations over its nuclear programme or risk being taken before the UN Security Council.

Bolton, renowned for his criticism of the United Nations, agreed that a multilateral approach to Tehran was the correct approach.

"We think the international pressure that the Security Council can bring on Iran may be what is necessary to get them to reverse the decision that they have made to pursue nuclear weapons," he said.

"Or, if it is not possible, that other steps we could consider through the Security Council can increase other kinds of pressure on Iran to get them to that point."

Asked if he was worried that the loss of credibility suffered by the Bush administration over the Iraq war would affect Washington's ability to pursue Tehran, Bolton, a close ally of US President George W. Bush, remained firm.

He said a successful outcome in Iraq was a priority for the president once the country was able to defend itself and had a representative government.

"There's no desire on our part to stay any longer than is necessary, but it cannot be a situation where the difficulties that we encounter in Iraq stop us from taking the necessary steps against countries like Iran seeking nuclear weapons," said Bolton.

Since the presidential election victory of Mahmoud Ahmadinejad, Iran has hardened its position on the nuclear problem by rejecting proposals that it abandon fuel cycle technology in return for incentives and resuming uranium conversion work in defiance of an agreement with Britain, France and Germany.

Bolton gave the exclusive interview to BBC2's flagship Newsnight programme.

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