Rob Watson: "Richard Butler, says... Iraq still has questions to answer"

In a report to the UN Security Council, Mr Butler says tests conducted by an American laboratory showed evidence of VX, but subsequent examinations in France and Switzerland were inconclusive.

Iraq 'may have tampered with evidence'

The report suggests that Iraq may have tried to decontaminate the samples between the first and second tests.

A US Army laboratory in June had found decayed VX nerve agent on missile warheads.

Iraq's parliament voted to suspend co-operation with the UN

But a second round of tests by French and Swiss laboratories found residue of a decayed decontamination compound that was not discovered by the original US tests.

The report says there was "no obvious explanation" why the original results did not find the decontaminant.

David Kay, a consultant for Science Applications International Corp., in Washington, and former UN weapons inspector said: "It's a clear sign that they tampered with the samples in the interim."

The experts' report does not suggest tampering.

But it says that the presence of the decontamination decay "conflicts with Iraq's declarations that the unilaterally destroyed special warheads had never been filled with any CW [chemical weapons] agents."

'Iraq must give explanations'

The report recommends that the UN mission in Iraq (UNSCOM) invites Baghdad "to explain first the origin and history of the fragments analysed by all three laboratories and then the presence of degradation products of nerve agents."

UN sanctions have hit hard the people of Iraq

Correspondents say the report will enable Britain and the United States to push in the Security Council for harder sanctions against Iraq since it had filled warheads with nerve gas.

But it will also enable China, France and Russia to resist such pressures by pointing to discrepancies.