The resolution, hammered out by France, Britain and Germany, was a painstaking compromise between hardline US demands to crack down on what Washington says is a covert Iranian nuclear weapons program and Tehran's threats to stop cooperating.

It is a possible turning point in an investigation begun by the International Atomic Energy Agency (IAEA) nearly two years ago.

"This is clearly a first step in the right direction. It will help mitigate international concern about the nature of Iran's program and over time should help to build confidence with regard to Iran's nuclear programme," IAEA chief Mohamed ElBaradei said after the agency's 35-nation board adopted the resolution by consensus.

Iran and the European trio are to begin talks in December on a package of rewards to Iran for suspending uranium enrichment, the key process using centrifuges to make fuel for nuclear reactors -- or the explosive core of atomic bombs.

Europe is ready to negotiate on trade, transfers of nuclear technology and help on security issues, such as creating a nuclear-weapons-free zone in the Middle East.

Iranian delegation chief Hossein Moussavian told AFP this could open up a new era of cooperation between Tehran and Europe after a quarter-century of tension.

But Jackie Sanders, head of the US team at the world's nuclear body, said Iran's 18 years of hiding sensitive nuclear activites and "continuing failure to cooperate fully and to act in good faith" had led the United States to lose "any illusions that Iran's ultimate intentions are peaceful."

Iran claims its nuclear program is a peaceful, civilian effort while Washington insists there is a covert weapons program and that the IAEA should take the Islamic Republic before the UN Security Council, which could impose economic sanctions.

But the IAEA welcomed Iran's enrichment freeze "as a voluntary confidence-building measure" in a resolution that was short on threats.

Sanders said Washington did not rule out moving on its own to take Iran to the Security Council.

The White House meanwhile said the world must "remain vigilant" about Iran's nuclear pursuits.

Iran's supreme leader Ayatollah Ali Khamenei said his country would press on with its nuclear programme and was not afraid of US pressure.

The adoption of the resolution ended a roller-coaster week of back-room talks after Iran's demand to exempt 20 centrifuges from the freeze sparked an outcry. Tehran later retracted the demand.

The IAEA has now sealed or otherwise controlled hundreds of components in verifying the freeze and is using cameras to watch the disputed centrifuges as a face-saving measure for Iran, diplomats said.

The IAEA is continuing to investigate Iran as ElBaradei has said that while no diversion of nuclear materials for weapons purposes has been detected, he could not rule out the possibility of covert activity.

But ElBaradei will no longer be automatically reporting to the board as he has for seven meetings since March 2003.

A key remaining question is the duration of the freeze. ElBaradei said a letter from Iran confirming the freeze did not put a "time line on the suspension."

ElBaradei said neither he nor the IAEA board "think that it (the suspension) should be linked to any talks with the Europeans."

But Iranian official Cyrus Nasseri told reporters that "the suspension will continue while negotiations move forward," hinting that Iran could end the freeze if the talks did not go well.

Delegation chief Moussavian said Iran planned to bring up the freeze when talks begin December 15.

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