President Bush warned Syria last night not to harbour any fleeing Iraqi leaders and insisted that Damascus has chemical weapons.

But he stopped short of threatening military action, insisting: “They just need to co-operate.”

Speaking to reporters after returning to the White House from Camp David, he said: “We believe there are chemical weapons in Syria.

“First things, first. We’re here in Iraq now and the thing about Syria is we expect co-operation.”

Mr Bush’s warning followed earlier comments by a former US foreign policy chief that the president should be impeached if he attacks Syria.

Lawrence Eagleburger, Secretary of State under George Bush Senior, said American public opinion would not tolerate action against Syria or Iran.

He was speaking as Colin Powell, the current Secretary of State, ramped up the pressure on Syria not to shield Saddam Hussein or his cronies.

Washington hawks are spoiling for a fight with Syria and Iran following the collapse of the Iraqi regime.

Defence Secretary Donald Rumsfeld yesterday said there was “no question” that Syria was harbouring senior Iraqi figures. But Mr Eagleburger, who accused Syria of having an outrageous record on terror, said an extension of the war was unthinkable.

“You saw the furore that went on before the President got sufficient support to do this,” he said. “This is still a democracy and public opinion rules. If George Bush decided he was going to turn troops on Syria now and then Iran he’d be in office about 15 minutes.

“If President Bush were to try it now, even I would feel he should be impeached. You can’t get away with that sort off thing in a democracy.”

Foreign Office minister Mike O’Brien arrives in Damascus today to tell Syria it has nothing to fear if it shuns terror and refuses to harbour Iraqi leaders.

President Assad denies any links to terror groups.