But as the last six monitors returned to Baghdad, the US and Britain remained sceptical about President Saddam Hussein's sincerity.

Rageeh Omar reports from Baghdad

The Iraqi authorities say they are ready to co-operate fully with the UN teams, but a senior adviser to Saddam Hussein has told the BBC that Iraq has already told the inspectors everything .

The return of inspectors follows the Iraqi president's last minute agreement to resume full co-operation in the face of US air strikes.

They are expected to resume their work with routine inspections, visiting sites and facilities which have been installed with surveillance equipment.

General Amer Al Sa'di: "Iraq has a just cause"

There they will check the cameras have not been tampered with and will change video tapes.

Later, inspectors specialising in unannounced lightning visits to suspected sites are due in Baghdad.

Unscom, the body overseeing inspections, says there is still a vast array of materials and documents which have yet to be turned over, particularly in the biological field, which the UN has described as "a black hole".

Iraq flatly denies this.

Butler: 'I hope to God they keep their promise'

Chief weapons inspector Richard Butler has said it is Iraq's last chance to tell the truth about its weapons programme.

But the head of Iraq's chemical and geological programme, General Amer Al Sa'di insisted they had already been doing so.

"We have told everything and we cannot prove the negative. It is for Unscom to come up with evidence," he added.

Mr Al Sa'di said eight years of seemingly endless inspections were enough and that Iraq's demand for an immediate end to sanctions was a just one.

Mr Butler would not speculate on whether Iraq had allowed the inspectors back simply to avoid military attack or was really willing to co-operate.

"The [UN] Security Council decided to take at face value their pledge, as did President Clinton," he told the BBC.

"Everyone is saying this is it. This is the end game. It's real. They have made a very serious promise in the face of very serious force. I hope to God they keep their promise."

The US and UK have warned that attacks could come at a moment's notice if Iraq fails to give the UN full co-operation.

Threat remains

Unscom's main task is stopping Iraq's previously substantial chemical and biological weapons programme, which the country maintains is finished.

US build-up in the Gulf is being scaled down

The US does not believe this and says Iraq still has the ability to grow biological agents - an allegation denied by Iraq.

The inspectors now hope to use the renewed threat of military action to discover the truth, and the US warns that Iraq's promise of co-operation will be aggressively tested.

In the meantime the US build-up in the Gulf is to be scaled back.

On Saturday the US and UK were only hours away from launching an attack when the Iraqi leader backed down.