The former Australian diplomat said that when he headed the UN team in Iraq from 1997 until 1999, he saw intelligence which seemed to indicate Syria had helped conceal Iraq's weapons of mass destruction (WMD).

"I was shown some intelligence information, from overhead imagery and so on, that the Iraqis had moved some containers of stuff across the border into Syria," Butler told ABC Radio.

"We had reason to believe that those were containers of chemical weapons and perhaps some other weapons.

"I don't believe the Iraqis wanted to give them to Syria, but I think they just wanted to get them out of the territory, out of the range of our inspections."

He said Syria was prepared to be the custodian of the WMD, but he did not know what had happened to them.

Butler said he had no doubt Iraq had WMD, but was unsure whether they would be found.

"Do they exist? No question. I knew that, Hans Blix knew that, the UN Security Council knows that, the permanent members of the Security Council knew that because some of them kept the receipts," Butler said.

"Will they find them? I don't know if they will find them. The Iraqis could have destroyed them, or hidden them, or moved them across the border...to Syria."

Butler, who vehemently opposed Australia's participation in the war, aired his views as the United States turned up the heat on Syria, accusing it of supporting terrorists, harbouring Iraqi leaders and having its own WMD, including the deadly nerve gas sarin.

US officials warned Damascus not to allow any senior Iraqi leaders to escape into Syria in an effort to flee coalition forces.

Syria denied the allegations, claiming Washington was trying to divert attention from the deepening chaos and looting in Iraq.

Australian Foreign Minister Alexander Downer said Canberra was also aware of intelligence reports that Iraqi weapons, including chemical weapons, may have been moved into Syria.

But he ruled out the possibility of a military attack on Syria, saying diplomatic pressure would be placed on Damascus because of its decision to leave open its border with Iraq and to allow Iraqi figures to escape.

Australia, meantime, announced it is sending 12 specialists to Iraq within a week to help in the search for WMD.

Defence Minister Robert Hill agreed the search might face criticism because it would not have UN authority, but he doubted the UN Security Council would be up to the task anyway.

"We are not so much interested in how others might perceive the process," Hill told reporters in Canberra. "We're interested in a process that can best assure us that the threat of weapons of mass destruction has been removed."

He said there are hundreds of sites to be examined in the continuing search for weapons of mass destruction and the coalition partners could not afford to wait.

"If we wait, the window of opportunity will be lost, the evidence will go cold," he said.

SPACE.WIRE