Iranian officials said Ahmadinejad would make new proposals to defuse suspicion over Tehran's nuclear weapons ambitions when he addresses the opening day of a three-day UN summit.

But he will be flying into a determined effort by US President George W. Bush to rally support for possible UN sanctions against the Islamic Republic for resuming sensitive work on uranium conversion.

"Iran with a nuclear weapon will be incredibly destabilizing. And therefore, we must work together to prevent them from having the wherewithal to develop a nuclear weapon," Bush said Tuesday at the White House.

Even without the nuclear dispute, the hardline Ahmadinejad was not destined to find a warm welcome from a country whose president has labeled Iran a charter member of the "axis of evil."

The US Department of Homeland Security initially refused the Iranian a visa because of suspicions he was involved in the 1979 seizure of diplomats at the US embassy in Tehran.

The State Department intervened to allow his visit but made it clear that "unresolved questions" remained about Ahmadinejad's militant past. "We have not forgotten that," said department spokesman Sean McCormack.

But the 46-year-old Ahmadinejad will seek to broaden Iran's international support in the nuclear row on his first foray into world politics since his shock election as president in June.

On the eve of his departure for New York, the former commando said he was facing "a sensitive period in history where the Iranian nation can identify its friends and enemies."

"We expect all the free and independent nations of the world to support Iran in its logical and principled stance," he said, insisting on Iran's "legitimate and recognised rights to have nuclear technology for peaceful purposes."

Iranian officials have hinted Ahmadinejad will pledge to cooperate with non-proliferation safeguards overseen by the United Nations' International Atomic Energy Agency (IAEA).

But such a proposal is certain to fall short of demands by the European Union and United States that Iran abandon uranium enrichment altogether.

Ahmadinejad will address the United Nations at a time when the United States and European Union are looking to haul Iran before the UN Security Council for activities linked to the production of atomic bombs.

Iran resumed fuel-cycle work in August after the breakdown of talks with Britain, France and Germany on a package of economic and security incentives to persuade Tehran to renounce its nuclear aspirations.

But Iran, which steadfastly maintains its nuclear program is strictly peaceful, issued another blunt warning Tuesday to the EU-3 against referring their standoff to the world body.

Senior national security official Ali Agha Mohammadi said the three countries were "mistaken on our policies, and think that if they increase the pressure we will back down," according to the student news agency ISNA.

"This is an error because if they do such a thing, the Iranian strategy will also be to raise the stakes in response," said Mohammadi, spokesman for Iran's Supreme National Security Council.

With the United States pressing for the support of China, Russia and India when the IAEA takes up the matter on September 19, Ahmadinejad will be doing some lobbying on his own.

While he has no plans to meet with leaders of the EU-3 countries, Ahmadinejad is to confer with Russian President Vladimir Putin in New York.

He is also expected to propose widening the nuclear talks to include more sympathetic parties such as Non-Aligned Movement members Malaysia and South Africa that have balked at imposing UN sanctions.

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