Alan Little in Baghdad: "We have again drawn closer to the edge"

In the 18-page letter, Iraqi Deputy Prime Minister Tariq Aziz says papers asked for by weapons monitors are either irrelevant or non-existent.

And he accuses chief weapons inspector Richard Butler of conducting a fishing expedition with his repeated requests for 12 categories of documents relating to Iraq's warfare programme.

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Mr Aziz argues that opening up the archives could jeopardise the country's national security.

The Security Council is due to discuss the issue on Tuesday.

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Mr Butler, head of Unscom which is in charge of dismantling Iraq's arms of mass destruction, has said it is too early to talk of military action against Iraq.

"Talk about their shortfall on documents leading automatically to some kind of enforcement is a bit exaggerated," he added.

Mr Butler has called the commission's data on biological warfare a "black hole".

But Mr Aziz disputes this in his letter to the UN.

"Iraq stated on several occasions that there are no biological weapons on Iraq's territory since July 1991" and Unscom has found nothing to contradict this, he says.

Mr Aziz says Iraq has provided Unscom with 1,760 documents, three films and four video tapes.

This is on top of 680,000 pages of documents and a large number of videos and microfilms handed over in 1995 following the defection of President Saddam Hussein's son-in-law.

After Hussein Kamal's defection to Jordan, he was lured back to Baghdad and killed.

Surprise weapons inspections

As the row over the missing documents escalated, Iraq reported that Unscom teams had carried out nine surprise inspections of sites on Monday.

These included a tobacco factory not placed under permanent monitoring, an Iraqi official said.

Unscom was unavailable for comment on the report of snap visits.

After delivering Mr Aziz's letter, Iraq's ambassador to the UN, Nizar Hamdoon, stressed his government was still committed to co-operating with the monitors.

''With this letter....I'm sure they [the international community and the Security Council] will see that the whole issue of the documents has really been overblown,'' he said.

'Butler's attack pretext'

The current impasse comes a week after Iraq agreed the inspectors could have unconditional access to weapons sites.

The US and UK have made it clear they will launch air strikes without warning if Iraq does not co-operate.

Earlier Iraq accused the US and UK of manufacturing a new crisis to justify military intervention in the Gulf.

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Mr Aziz said Mr Butler was creating a "superficial pretext" for attack by demanding imaginary weapons documents after Iraq has already made them all available.

The UN Secretary-General Kofi Annan's special envoy, Prakash Shah, has arrived in Baghdad seeking to resolve the dispute and Iraqi officials have said key documents will be handed over during his visit

In the UK a meeting was convened of 15 Iraqi opposition groups to urge them to work together in the campaign to remove President Saddam Hussein.