Documents bearing the seal of Saddam Hussein's secret service were seized early Saturday by U.S. forces during a raid of a Baghdad (search) community hall.

The documents, which are being handed over to senior intelligence analysts, mentioned Iraq's nuclear program and may possibly contain information regarding Iraq's weapons of mass destruction (search).

Americans also are mounting a "very aggressive effort" to follow up on information from a captured top aide to Saddam Hussein that the former Iraqi president is alive, said Sen. Pat Roberts, chairman of the Senate Intelligence Committee (search ).

The Iraqi intelligence haul came on the sixth day of a nationwide sweep to seize weapons and insurgents. So far, the military has conducted 90 raids and netted 540 suspects, a coalition spokesman said. No figure was given on how many had been released.

"It's potentially significant," said Capt. Ryan McWilliams, an intelligence officer with the Army's 1st Armored Division, who examined the documents. He said U.S. forces have been combing Iraq for clues to the country's banned nuclear, chemical and biological weapons programs. The searches have so far failed to prove that Iraq harbored unconventional weapons President Bush cited as the justification for war.

In his weekly radio address Saturday, Bush defended initial administration claims about the existence of the weapons but did not promise they will be found, as he had on other occasions until recently. The president said documents and suspected weapons sites were looted and burned "in the regime's final days."

"We are determined to discover the true extent of Saddam Hussein's weapons programs, no matter how long it takes," Bush said.

The search for Saddam and his sons also has been fruitless so far.

On Saturday, The Washington Post and The New York Times reported that Saddam's top aide, captured Monday, has told U.S. interrogators that the deposed leader and his two sons survived the war and were hiding north of Baghdad.

The claim, attributed to Abid Hamid Mahmud al-Tikriti (search ), could not be verified. The White House refused comment.

Sen. Roberts, R-Kan., confirmed on Saturday that Mahmud had told U.S. interrogators, "There is every likelihood that Saddam is alive."

"We have now mounted a very aggressive effort to follow up on what he has told, basically, his captors," Roberts said at a news conference in Topeka, Kan. "If he is alive — and there's still a lot of speculation — I think he will be found," he added.

Roberts said reports that Saddam is alive give his supporters "credibility in their own minds" and could be fueling anti-American attacks against U.S. forces in Iraq.

"That's why they're staging this, basically, guerrilla war against our forces, and we're suffering casualties," Roberts said.

Saturday's raid in Baghdad's Azamiyah district nabbed dozens of military radios, cryptography equipment and mapmaking plotters. Most equipment appeared to be old. It included equipment made by U.S. and European companies like Motorola and Thompson.

McWilliams said informants told him Iraqi intelligence officials stashed the goods there in the last days of Saddam's regime. He added that the stash would be handed over to intelligence analysts at the division's headquarters at Baghdad International Airport to see if they relate to banned Soldiers with flashlights examined documents strewn across the floor of two rooms above a funeral parlor. An Arabic interpreter pointed out Top Secret and Personal markings.

One document, dated Feb. 7, 1998, appeared to be a manifest for secure communications equipment. The memo, sent from the National Security Council of Iraq, was addressed to the Iraqi Nuclear Organization, with a carbon to the Mukhabarat, the secret intelligence service.

Saturday's search — a job usually handled by U.S. intelligence operatives — fell to the Gunners, a field artillery regiment, used to firing cannons in conventional battles.

Since June 15, the Gunners have been one of the busiest U.S. units in Baghdad, seizing more than 60 suspects along with weapons, propaganda leaflets and cash.

The Gunners get raiding pointers, intelligence and interrogation help from U.S. Special Forces The mainly Sunni Muslim Azamiyah district has been the site of sophisticated ambushes on U.S. forces. The last time Saddam was seen in public — in the war's waning days — was in Azamiyah, and the neighborhood put up some of the toughest resistance to the U.S. invasion.

"It's just infested with guys who think at the highest level," said Col. Bill Rabena, the Gunners' commander. "These guys are organized. It's not just a bunch of thugs with RPGs," or rocket-propelled grenades.

To help maintain security in postwar Iraq, U.S. officials will soon announce the creation of a new Iraqi army that will be open to soldiers of the former regime, the coalition spokesman said.

"It's going to be an army, not a secret police. It's going to be professional, not political. ... And it will be open to former members of the Iraqi military," he said.<< />

After Saddam's ouster, the entire Iraqi military was dismissed. Iraqi police officials say that former Meanwhile, an estimated 2,000 Iraqi Shiites staged a demonstration outside the gate of the U.S. political and military headquarters.

"We want an honest government, not thieves," read one banner among the throng. "Iraq should be ruled by no one but its people," read another. American soldiers on Wednesday shot and killed two protesters after a similar demonstration by former Iraqi soldiers turned into a stone-throwing melee.

A three-member delegation was allowed into the compound to present demands for the speedy After the negotiators emerged, Raed al-Kazimi, a senior Shiite leader, told The Associated Press that the Americans "agreed in principle to some of the demands." But he said the Shiite leadership will take action if the Americans don't live up to their word. He did not elaborate.

The Associated Press contributed to this report.