Political and military officials in Poland on Saturday insisted their troops in Iraq have found poison gas in newly unearthed warheads, a day after multinational forces said no chemical agents were found.

"In each of the missiles found, the presence of a chemical substance was found. It was cyclosarin," a spokesman for the Polish contingent in Iraq, Colonel Robert Strzelecki, said.

"They were missiles that were made 15 years ago, which should have been destroyed and were not. They would certainly have been very dangerous had they fallen into the hands of terrorists," said deputy Defence Minister Janusz Zemke.

Another senior Polish intelligence official went to the extent of saying that "terrorist" groups were seeking to acquire the weapons.

Hotly disputed

But the strident Polish claims have come under scrutiny following strong denials from the multinational forces in Baghdad.

In a statement, multinational forces pointed out that the 122mm warheads had tested negative for chemical agents.

"Those 16 rounds were all empty and tested negative for any type of chemicals," it said.

Finding weapons of mass destruction in Iraq is immensely important for the United States and its allies. Iraq's invasion and occupation last year had been under the pretext of finding Iraq's WMD arsenal, but none has been found so far, with several US experts saying US intelligence had been misled.

Though disputed, Washington on Thursday announced that Polish troops have discovered more than a dozen warheads containing mustard or sarin gas.

Polish occupation forces patrol large areas of the country south of Baghdad, heading a 6500-strong multinational force including 2500 Polish troops.