The US administration says the discovery of empty chemical warheads in Iraq is "troubling and serious".

A spokesman for President George W Bush also challenged Iraq's assertion that the weapons were listed in the arms declaration given to the United Nations last month.

US Secretary of State Colin Powell told a German newspaper he believed that by the end of this month Iraq would be shown to be not co-operating with the weapons inspectors.

Hans Blix: Discovery "not very good"

Later on Saturday, anti-war protesters are due to hold a series of demonstrations in cities in the United States, Europe, the Middle East and Japan.

European leaders have been warning against unilateral military intervention in Iraq and urging more time for United Nations inspections.

Iraqi President Saddam Hussein warned the US on Friday it would be defeated if it tried to attack his country.

'Not disarming'

Mr Bush's spokesman Ari Fleischer rejected Iraqi assertions that the warheads discovered on Thursday had been included on its arms declaration submitted last month.

"The fact that Iraq is in possession of undeclared chemical warheads, which the United Nations says are in excellent condition, is troubling and serious," he said.

"Under the UN resolution, Saddam Hussein has an obligation to disarm. It has become increasingly clear that he is not doing so."

We believe that at the end of the month it will be convincingly proven that Iraq is not co-operating US Secretary of State Colin Powell

The warheads are being tested to determine if they ever contained banned chemicals - Baghdad says they are merely empty rockets that have expired.

"We believe that at the end of the month it will be convincingly proven that Iraq is not co-operating," Mr Powell said in an interview with Saturday's Sueddeutsche Zeitung, published in German.

Mr Powell said the United States did not require a second resolution on Iraq - seen by many countries as a necessary step before war.

However, a State Department spokesman downplayed speculation that Mr Powell was about to produce some new and convincing evidence.

Clarifying Mr Powell's comments, spokesman Richard Boucher said that a "persuasive case" for Iraq's non-compliance with UN resolutions would be put forward at the end of the month.

Co-operation urged

Earlier, French President Jacques Chirac delivered a blunt warning against any unilateral military action, saying it would break international law.

He said UN weapons inspectors must be given the necessary time to complete their work in Iraq.

KEY DATES

19 Jan - Blix meets top Iraqi officials in Baghdad 27 Jan - First full report on inspections presented to UN 29 Jan - UN discusses report 31 Jan - Bush meets Blair 15 Feb - Anti-war protests across Europe 27 Mar - Blix submits new report to UN

Next steps in full

Mr Chirac urged Baghdad to give clear signs that it is co-operating with the weapons inspectors, but warned any decision on military action had to be made by the Security Council as a whole.

Russia, which like France has a power of veto in the UN Security Council, warned against jumping to conclusions over the warheads discovery.

The UK prime minister's office said Tony Blair expressed his strong support for the inspectors and paid tribute to their work at his meeting with chief UN arms inspector Hans Blix on Friday.

Mr Blair welcomed the intensification of the inspections and stressed it was important for President Saddam to take full advantage of this opportunity to disarm, his office said.

Saddam Hussein marked the 12th anniversary of the start of the Gulf War on Friday with a defiant speech in which he warned that US-led forces faced certain death if they attacked Iraq.

He made no reference to the 11 warheads found on Thursday at the Ukhaider military storage facility.