The United States has warned Saddam Hussein that Iraq must act now to avoid an American-led attack, amid signs that Baghdad is moving to make concessions in the crisis.

With US Secretary of State Colin Powell by his side, President George W Bush declared that "the game is over" and urged hesitating allies to join in disarming Iraq.

Saddam Hussein was given a final chance, he is throwing that chance away President Bush

Full text of Bush statement

His warning came as Iraq accepted one of the main demands of United Nations weapons inspectors by allowing a scientist to be interviewed alone for the first time.

The UN inspectors are due to present a key report on Iraqi co-operation to the Security Council on 14 February.

In his comments on Thursday, Mr Bush said that the US would welcome and support a new Security Council resolution - as long as it endorsed its previous demands for Iraqi disarmament.

But he made it clear that if the Council did not act, then the US and a growing coalition would take whatever action was necessary to disarm Saddam Hussein.

In a related development, Russia - also one of the Security Council's permanent members - said there is no need yet for a second resolution.

Further action depended on the inspectors' reports, Russian Deputy Foreign Minister Yuri Fedotov was quoted as saying by the Interfax news agency.

"Decisions of the Security Council must be aimed at settling the Iraqi issue and not complicating it," he said.

Iraqi climbdown

An Iraqi scientist was interviewed for more than three hours without the presence of official government monitors, a UN spokesman said on Friday.

"A private interview was conducted with an Iraqi biology scientist alone," Hiro Ueki said.

	:	Powell's report
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And UN sources in Baghdad have told the BBC that they have had indications that Iraq is prepared to make some new and significant concessions.

Speaking to the BBC's Rageh Omaar, the sources said that chief inspectors Hans Blix and Mohamed ElBaradei were returning to the Iraqi capital on the expectation that Iraq was prepared to change its position on a number of sticking points.

The sources said the Iraqi authorities had indicated they may grant permission on the use of U-2 surveillance planes to help the work of the inspectors.

But the officials say Mr Blix and Mr ElBaradei, who are due in Baghdad at the weekend, will need to come away with real progress on substance.

President Bush brushed aside the latest developments in Baghdad, saying he had no doubt that Iraq would "start another round of empty concessions" as it came under increasing pressure.

"Saddam Hussein was given a final chance. He is throwing that chance away," Mr Bush said, referring to the Security Council resolution unanimously approved in November paving the way for new arms inspections.

"The dictator of Iraq is making his choice," he added.

"The UN must not back down," Mr Bush said. "All the world can rise to this moment."

Military build-up

The president's public position on Iraq is unrelenting. But the BBC's Washington correspondent Justin Webb says if the UN inspectors are impressed by a newly co-operative mood in Baghdad, the White House has not completely closed the door on diplomacy.

Meanwhile the military build-up in and around the Gulf is continuing to gather momentum.

CURRENT SECURITY COUNCIL

For military action: US*, UK*, Spain and Bulgaria Sceptics or opposed: France*, Russia*, China*, Germany and Syria In doubt: Angola, Cameroon, Chile, Guinea, Mexico and Pakistan Nine votes and no veto required to pass a resolution *veto-wielding countries

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The latest deployments involve the 23,000 troops of the US army's crack 101st airborne division, a fifth American aircraft carrier - the USS Kitty Hawk - and a third of Britain's front-line combat jets.

More than 200,000 US military personnel are now in or on their way to the region along with about 40,000 British troops.

US Defence Secretary Donald Rumsfeld is visiting Italy and Germany to press the case for the possible use of force against Iraq.

After Mr Powell's presentation to the Security Council on Wednesday, Washington wants to keep up the momentum, a BBC correspondent says.

Observers say there may also be hints from fellow members of the Council that opposition to a new resolution may be softening.

French Foreign Minister Dominique de Villepin on Wednesday put renewed stress on the urgency of Iraq complying by the end of next week.

But our correspondent says that Mr Bush was very careful in his choice of language - saying the US would welcome a new resolution, but it does not want or need one to make the use of force legitimate.