"We believe there are chemical weapons in Syria," he told journalists on the White House lawn.

"The Syrian government needs to cooperate with the United States and our coalition partners. It must not harbor any Baathists, any military officials who need to be held to account for their tenure" in Iraq, Bush added.

Asked if Syria could face military action, Bush said: "They just need to cooperate."

The United States has long claimed that Syria has stockpiles of chemical weapons.

The under secretary of state for arms control and international security, John Bolton said in May 2002 that Syria "has a stockpile of the nerve agent sarin and is engaged in research and development of the more toxic and persistent nerve agent VX."

He also said Syria was "pursuing the development of biological weapons and is able to produce at least small amounts of biological warfare agents."

Earlier Sunday, Defense Secretary Donald Rumsfeld said that US forces have engaged Syrians in combat in Baghdad recently, reiterating charges that the Syrians have taken in senior officials of the Iraq regime.

The Bush administration has stepped up its criticism of Syria during the last week, and Secretary of State Colin Powell joined the fray Sunday, warning the country against offering safe haven to fleeing members of Iraqi regime.

"We think it will be very unwise if, suddenly, Syria becomes a haven for all these people who should be brought to justice, who are trying to get out of Baghdad," Powell said in a BBC television interview.

Syria had been a concern in Washington "for a long period of time", Powell said, alleging that Damascus was a state sponsor of "terrorism" and a supplier of military supplies to Saddam's regime.

Bush on Friday urged Syria to shut its borders to fleeing followers of Saddam Hussein and turn over any who have already found "safe haven" in Iraq's western neighbor.

"We expect them to do everything they can to prevent people who should be held to account from escaping in their country," he said.

"And it they are in their country, we expect the Syrian authorities to turn them over to the proper folks," said Bush.

Imad Moustapha, the number two in the Syrian embassy here, flatly denied US accusations that Syria was assisting members of Saddam Hussein's regime, harboring terrorists or producing weapons of mass destruction.

"It's been a campaign of misinformation and disinformation about Syria since even before the war started. This is just an ongoing series of false accusations," Moustapha told NBC News program "Meet the Press".

He said Syria was willing to accept international inspections to allay US fears that it has weapons of mass destruction and urged Washington to help rid the entire Middle East -- including Israel -- of such arms.

"We will not only accept the most rigid inspection regime, we will welcome it heartily," Moustapha said.

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