"Despite many efforts to locate and destroy Iraq's pre-Gulf war chemical munitions, filled and unfilled pre-Gulf war chemical munitions are assessed to still exist," it says.
The lawmakers cited the report as validation of the US rationale for the war, and stressed the ongoing danger they pose.
"This is an incredibly -- in my mind -- significant finding. The idea that, as my colleagues have repeatedly said in this debate on the other side of the aisle, that there are no weapons of mass destruction, is in fact false," Santorum said.
A Pentagon official who confirmed the findings said that all the weapons were pre-1991 vintage munitions "in such a degraded state they couldn't be used for what they are designed for." The official, who asked not to be identified, said most were 155 millimeter artillery projectiles with mustard gas or sarin of varying degrees of potency.
"We're destroying them where we find them in the normal manner," the official said. In 2004, the US army said it had found a shell containing sarin gas and another shell containing mustard gas, and a Pentagon official said at the time the discovery showed there were likely more. The intelligence overview published Wednesday stressed that the pre-Gulf War Iraqi chemical weapons could be sold on the black market.
"Use of these weapons by terrorists or insurgent groups would have implications for coalition forces in Iraq. The possibility of use outside Iraq cannot be ruled out," it said.
Santorum said the two-month-old report was prepared by the National Ground Intelligence Center, a military intelligence agency that started looking for weapons of mass destruction in Iraq when the Iraq Survey Group stopped doing so in late 2004.
Last year the head of Iraq Survey Group, Charles Duelfer, said that insurgents in Iraq had already used old chemical weapons in their attacks. Nevertheless, "the impression that the Iraqi Survey Group left with the American people was they didn't find anything," Hoekstra said.
"But this says: Weapons have been discovered; more weapons exist. And they state that Iraq was not a WMD-free zone, that there are continuing threats from the materials that are or may still be in Iraq," he said.
Asked just how dangerous the weapons are, Hoekstra said: "One or two of these shells, the materials inside of these, transferred outside of the country, can be very, very deadly."
The report said that the purity of the chemical agents -- and thus their potency -- depends on "many factors, including the manufacturing process, potential additives, and environmental storage conditions."
"While agents degrade over time, chemical warfare agents remain hazardous and potentially lethal," it said.
Reporters questioned the lawmakers as to why the Bush administration had not played up the report to boost their case for continued warfare in Iraq.
"The administration has been very clear that they want to look forward," Santorum said. "They felt it was not their role to go back and fight previous discussions."
Fear that Saddam Hussein might use his alleged arsenal of chemical and biological weapons was a reason US officials gave for launching the March 2003 invasion of Iraq.