Efforts to complete the draft continued Thursday as US President George W. Bush joined China in supporting a Russian plan to halt the Iran nuclear crisis.

Russia has offered to manufacture nuclear fuel for Iran and collect the waste so that it cannot be used for nuclear weapons development.

Although Iran has said it is interested in the idea, the United States continues to lobby hard to get the International Atomic Energy Agency to refer Iran to the UN Security Council.

The United States, Britain, Germany and France were haggling with Russia and China over the wording of the draft resolution for an emergency IAEA meeting in Vienna on February 2.

The confidential draft -- read to AFP -- recommends to the Security Council "that it consider making clear to Iran that outstanding questions" can be resolved by Iran "responding" to IAEA calls for a suspension of its nuclear fuel work.

Russia is resisting the pivotal clause because it fears Tehran's failure to meet the demand would open the way to a Security Council escalation and possible sanctions, said a senior diplomat, who is close to the talks but asked not to be named.

According to the diplomat, the draft text shows a line crossing out the crucial clause. The diplomat said this had been done by the Russian representative to talks in Vienna in order to clear the way for a new wording.

The IAEA meeting was called after Iran this month resumed work on uranium enrichment, the process that makes fuel for nuclear reactors but can also become the raw material for bombs.

While Washington charges that Iran is seeking atomic weapons, Tehran insists its programme is peaceful.

The European trio, who are spearheading European Union talks with Iran, drew up the draft text, a senior diplomat close to the talks said.

Russia wants to change the key clause so that the IAEA board of governors just informs the Security Council about developments in Iran but "decides not to take any action," the senior diplomat said.

"The Russians object that if the Council is empowered to take any sort of action, that this will go further, an automatism that will set off a chain of reactions," said the diplomat.

The diplomat said that "if Iran does not do what the resolution tells them, then this could lead to sanctions, or even more," a reference to military action, under the UN Charter.

A second diplomat said the Russians want the crackdown on Iran to be a "two-step" process, with the Security Council being informed of the matter. But any decision on calling for enforcement action would come after a pause for diplomacy until a regular IAEA board meeting on March 6.

Bush on Thursday gave public backing to the Russian compromise but said the United States is not easing efforts to refer Iran to the Security Council.

China and IAEA chief Mohamed ElBaradei have also backed the move.

The US State Department has expressed fears that Iran could be seeking to buy time through the Russian proposal.

"The Russians came up with the idea and I support it. And the reason why I think it makes sense is because I do believe people ought to be allowed to have civilian nuclear power," Bush told a White House press conference.

"However, I don't believe nontransparent regimes that threaten the security of the world should be allowed to gain the technologies necessary to make a weapon. And the Iranians have said, 'We want a weapon'. And it's not in the world's interests that they have a weapon."

Bush stressed that the United States want to end the crisis through diplomatic efforts. But it is also lobbying aggressively for a UN referral.

Diplomats said the United States as well as the European trio were pushing hard in Vienna to rally support on the IAEA board.

One diplomat said US officials were saying that "Iran is a direct threat to US national security and that the United States will not tolerate an Iranian nuclear weapons programme or enrichment capability because of the nature of the regime."

"The Americans made very clear that they want action at this board," a diplomat said.