Updated

The discovery of 3,000 chemical suits in an Iraq hospital that was used as an enemy military base raised concern that Saddam Hussein's regime was prepared to use chemical weapons, U.S. Central Command said Wednesday.

"What we found at the hospital reinforces our concern," Brig. Gen. Vincent Brooks said during a news briefing at Doha, Qatar. "We are well-prepared to deal with the potential use of chemical weapons."

In addition to the chemical suits, Marines found and confiscated gas masks and nerve gas antidote injectors in the hospital near Nasiriyah.

U.S. intelligence has picked up signs suggesting the closer ground troops get to Baghdad, the greater the chance they will face chemical weapons, Defense Secretary Donald H. Rumsfeld said Tuesday.

There may be a "tripwire" -- a line drawn on a map of Iraq -- indicating the point at which Iraqi troops near Baghdad are authorized to unleash harmful chemical weapons on incoming allied forces.

The Army's 3rd Infantry Division has drawn to within about 50 miles of Baghdad, with the Medina armored division of Saddam's Republican Guard in its path.

Elements of the 1st Marine Division are approaching the capital from a more easterly direction, and some analysts believe the Army's 101st Airborne Division, now in southern Iraq, will join the battle for Baghdad.

Asked about reports that Republican Guard forces ringing Baghdad have been given authority to use chemical weapons, Rumsfeld cited "scraps" of intelligence suggesting that the closer the 3rd Infantry gets to the capital, the greater the danger.

He did not offer details of the intelligence indicators because "who knows how accurate they are," he said.

Iraq denies it has any chemical or biological weapons.

The Bush administration insists it has both and is trying to gain nuclear weapons. The risk of Iraq using chemical, biological or nuclear weapons or providing them to terrorist networks was the central reason President Bush went to war.

Gen. Richard Myers, chairman of the Joint Chiefs of Staff, said the commander of U.S. forces fighting the war, Gen. Tommy Franks, has plans in place should Iraq use chemical weapons.

Secretary of State Colin Powell, in an interview with France 3 television, cited speculation that "there is a box around Baghdad, that if we penetrate that box," Saddam would unleash a chemical attack. "If he did," Powell added, "it would not stop the [U.S.] assault."

He also told Fox News' Brit Hume that it would be no surprise if Saddam unleashed such weapons.

U.S. forces are equipped with full-body chemical protection suits and gas masks.

Rumsfeld also said U.S. and allied forces have taken in "excess of 3,500 Iraqi prisoners."

Rumsfeld tried to dampen public expectations that the war would be won quickly and to reiterate the message delivered daily by senior military commanders here and in the Gulf that the war is progressing as planned.

"We're still, needless to say, much closer to the beginning than the end," Rumsfeld said.

Rumsfeld brushed aside suggestions that U.S. war planners underestimated the Iraqis' will to fight and overestimated the ability of U.S. precision airstrikes against the pillars of Saddam's power to end the conflict before it reached the stage of having to initiate a battle for Baghdad.

Some private analysts, including former military officers, have suggested that the Army needs more armored forces in Iraq than the 20,000 troops of the 3rd Infantry Division, including forces that could better protect the 3rd Infantry's long and vulnerable supply lines.

The Army's 4th Infantry Division was expected to deploy toward the end of the week.

Also headed for Kuwait soon is the 3rd Armored Cavalry Regiment, followed by the 1st Infantry, the 1st Armored divisions from Germany, the 1st Cavalry Division and the 2nd Armored Cavalry Regiment, officials said.

The Associated Press contributed to this report.