Britain rejected complaints yesterday by Hans Blix, the head of the United Nations weapons inspectors in Iraq, that it was not providing enough intelligence on the location of weapons of mass destruction.

Britain´s intelligence organisations are helping the UN inspectors as much as they can without giving away sources and risking the lives of agents, officials said.

The Secret Intelligence Service, MI6; the Cheltenham-based signals intelligence organisation, GCHQ, and the Ministry of Defence, which deals with photographic and satellite intelligence, are providing a large amount of technical information.

Mr Blix said inspectors were at present not in a position "to confirm Iraq´s statements, nor in possession of evidence" to disprove them.

He complained to the BBC´s Today programme that his inspectors "don´t get all the support we need" from western governments.

"They have all the methods to listen to telephone conversations, they have spies, they have satellites so . . . they have a lot of sources which we do not have," he added.

The Foreign Office said Mr Blix´s remarks had been taken out of context and that he had acknowledged receiving useful intelligence from Britain and America.

But officials say there is always a limit to how much intelligence can be made public without revealing sources. This is especially true where UN inspectors are involved; they are prone to leaks.

According to former UN inspectors, the previous operation, Unscom, which searched for weapons in Iraq from 1991 to 1998 was penetrated, both in Baghdad and in New York, by Iraq as well as by several other governments.

The problem for Britain´s spies is that the Iraqis are mounting a highly complex operation to hide the key components and in particular chemical and biological agents, what Tony Blair described yesterday as playing "hide and seek" with the weapons of mass destruction.

That poses highly complex problems for the intelligence services. Details of the existence of the weapons of mass destruction and in particular their day-to-day movements is being kept to a very small circle of Iraqis.

Saddam Hussein is already paranoid about his security and is suspicious about anyone close to him. So western intelligence agents are in a dangerous enough position without putting themselves in even greater danger by giving the UN inspectors high-grade intelligence.

GCHQ is also extremely sensitive about its sources of intelligence, but for different reasons. The Iraqis employ great use of fibre-optic cables that make communications difficult to intercept.

The vehicles used to transport the weapons batches around the country must use some form of radio transmission to communicate but these are bound to use highly encrypted communications.

If GCHQ is able to decrypt them - far from certain - it will certainly not want to compromise high-grade intelligence material by passing it to UN inspectors.

Imagery intelligence, provided by coalition aircraft and spy satellites, analysed in Britain by the Joint Air Reconnaissance Intelligence Centre at Brampton, near Huntingdon, is the only information which can be safely passed on to the UN.

• American and British aircraft attacked Iraqi air defences in the southern "no-fly" zone yesterday in the fifth such raid in a week, it was reported in Washington. Baghdad said Iraqi anti-aircraft and missile batteries fired back. (© Copyright of Telegraph Group Limited 2002. 12/21/02)