Updated

Intelligence reports indicate a high risk that Iraq would use chemical weapons during a U.S.-led war to topple President Saddam Hussein, Pentagon officials said Tuesday.

The reports indicate Saddam has given field-level commanders the authority to use chemical weapons on their own initiative, without further directives from the Baghdad, Pentagon officials said.

"We continue to receive reports supporting the assertion that there is a high risk the Iraqi regime would use chemical weapons at some point during any conflict," Pentagon spokesman Bryan Whitman said Tuesday. It was the first explicit statement from the Defense Department discussing the chemical weapons risk.

Chief U.N. weapons inspector Hans Blix said he does not believe Saddam's government will use chemical or biological weapons even as a last resort because it would turn world opinion in favor of the United States.

"Some people care about their reputation even after death," he said.

President Bush and other U.S. officials say Iraq has stocks of chemical weapons, including the deadly nerve agents sarin, cyclosarin and VX and a mustard agent like that used in World War I. Saddam has repeatedly denied having chemical or biological weapons, the use of which has been outlawed for decades, although Iraq has acknowledged developing both before the 1991 Persian Gulf War and used them several times in the 1980s.

U.S. officials say they believe Iraq's chemical weapons are under the control of the Republican Guard, Saddam's best trained and most loyal troops. A large part of those forces is concentrated in and around Baghdad, where U.S. officials worry that fighting involving chemical weapons could kill many Iraqi civilians.

Most of Iraq's chemical arsenal, officials say, is loaded onto artillery and rockets that have a range of about a dozen miles or less.

Pentagon officials who discussed the chemical weapons issue on condition of anonymity said it was unclear what rank of Iraqi officers had been authorized to order the use of chemical weapons. Officials said it was doubtful the chemical authority went as low as company-level commanders, who are usually at captain's rank.

Coalition troops awaiting invasion orders have chemical protection gear and equipment that can detect clouds of chemical agents up to three miles away. American tanks and armored vehicles have filters designed to keep the troops inside safe from the deadly agents. Anticipating the possibility of chemical combat, U.S. troops have trained extensively on operating in a contaminated environment.

All of Iraq's chemical agents except sarin can linger in an area for hours or days. VX, the deadliest chemical weapon known, is a sticky liquid that is particularly long lasting and difficult to decontaminate.

U.S. officials have said they believe Iraq is most likely to use chemical weapons to cover a retreat or put down an internal uprising. Because U.S. forces are so well protected, chemical weapons could be used in an attempt to slow an American onslaught or keep the U.S. forces out of a particular area, rather than to kill large numbers of U.S. troops, officials say.

A chemical attack against Iraqi civilians also could bog down U.S. troops by creating a humanitarian crisis the American forces couldn't ignore.

In his war ultimatum given Monday night, President Bush explicitly warned Iraqi troops against using chemical or biological weapons, especially against Iraqi civilians. U.S. military leaflets, radio broadcasts and e-mails have carried similar warnings that any officers involved in chemical weapons use would be prosecuted on war crimes charges.