International experts searching for weapons of mass destruction barged into one of President Saddam Hussein's opulent, forbidden palaces from two directions today, testing Iraq's promise to comply with a U.N. Security Council resolution permitting unannounced inspections of any site in the country.

When the inspectors drove up to the front and rear entrances of Hussein's Sijood palace in central Baghdad, a site usually off-limits to all but a few of Hussein's top lieutenants, flustered guards initially blocked the convoy. But after about eight minutes, as Iraqi officials who had been trailing the inspectors barked into their radios and shouted at the palace guards, the black metal gates were pulled open and the inspectors drove up a palm-lined driveway toward a three-story, turquoise-domed brick building at the center of the vast compound.

U.N. officials did not say why they chose to visit Sijood today, what they were looking for or whether they found any evidence of chemical, biological or nuclear weapons. Western intelligence officials and analysts have long believed that Hussein has hidden evidence of a program to develop prohibited weapons in some of his secretive and garish palaces.

A U.N. spokesman here said "access to the entire site was provided without any difficulty" and that inspectors were able to search "every room, every corner" of the complex. Gen. Hussam Mohammed Amin, the chief Iraqi liaison with the inspectors, said "the inspectors were happy" with their visit.

The surprise visit, which came just one day after President Bush said his initial reading of Iraq's cooperation with the Security Council resolution was "not encouraging," could have been an effort by U.N. inspection leaders to send a signal to the U.S. government about Iraq's compliance with the inspection process, diplomats here said. Iraq's acquiescence to a spontaneous search such as the one today would have been unthinkable during earlier rounds of inspections, they added.

For most of the 1990s, Hussein's government refused to allow inspectors into Sijood and other presidential palaces on the grounds that it would violate Iraq's sovereignty. But in February 1998, after President Bill Clinton threatened to launch military strikes against Iraq, U.N. Secretary General Kofi Annan hammered out a compromise that allowed inspectors to visit the palaces and other sensitive sites if they provided advance notice and were accompanied by a team of diplomats.

The inspectors searched Sijood and seven other presidential palaces in April 1998 but reported that most of the 1,058 buildings they saw in those compounds were largely empty. Today the inspectors had to go through none of the earlier formalities. They simply got in their white sport-utility vehicles at the U.N. headquarters here and drove to Sijood. "Open the gate," one inspector told the guards at the front entrance. "We want to come in."

The inspection this morning was at one of the more sensitive of the previously visited sites, but there are still others that have never been inspected and that might provoke a confrontation if the U.N. officials demand entry.

Under a Security Council resolution approved unanimously last month, Iraq could face unspecified "serious consequences" if inspectors are denied access to any person or place they want to see. The resolution specifies that the inspectors are not required to seek permission for their searches or provide advance notice.

Iraq has insisted that it does not possess, and is not developing, weapons of mass destruction. Amin said Iraq would reaffirm that position in a long-awaited declaration of its weapons programs it must submit to the Security Council by Sunday. Amin said the declaration, which is expected to be voluminous, "will include new elements, but those new elements don't mean that Iraq has weapons of mass destruction."

On Monday, Bush demanded Iraq include every detail of its weapons and missile programs in the declaration, warning that "any act of delay, deception or defiance will prove that Saddam Hussein has not accepted the path of compliance and has rejected the path of peace."

U.N. inspectors first arrived in Iraq in 1991, shortly after the Persian Gulf War. They were credited with destroying tons of chemical and biological weapons and dismantling the country's nuclear weapons program. But the monitoring ended in 1998 as disputes grew over the inspectors' access to sites and Iraqi objections that the United States used some inspectors as spies.

The dramatic visit to the Sijood palace came on the sixth day of renewed inspections. All 17 U.N. inspectors in Iraq -- a combination of nuclear, chemical and biological specialists as well as missile experts -- participated in the nearly two-hour search.

After they left, Iraqi officials permitted several dozen foreign journalists, who had been waiting outside, to enter the grounds and walk around the palace's soaring, eight-sided foyer for about 15 minutes. The journalists were prevented from entering other rooms in the main building -- plainclothes guards stood in front of closed wooden doors -- or from seeing inside other, smaller buildings. The high-walled compound stretches for about three city blocks in both length and width.

Video footage from Associated Press Television News showed inspectors wearing blue baseball hats walking through rooms and pausing to open every door and cupboard they could find. At one point, the chief field inspector, Demetrius Perricos, opened a white refrigerator and took out a small jar. After inspecting it, an Iraqi official accompanying him said, "I think you'll find it's marmalade."

Even with the restrictions for journalists, the ability to walk inside one of Hussein's palaces is an unheard-of opportunity in Iraq. Normally, taking photographs of so much as the exterior walls of a palace from a moving car can result in punishment.

The few pieces of visible furniture in the lobby and a few connecting hallways were far less elegant than the surroundings, suggesting that Hussein probably does not spend much time, if any, at Sijood. A dining table was surrounded by 10 chairs with peeling paint. A lime green fly swatter was sitting on the buffet table, albeit in a seemingly custom-built wooden rack.

Hussein is believed to have more than 50 palaces throughout the country. He reportedly moves among them on a regular basis out of fear for his safety.

The Sijood palace was severely damaged by bombs during the Gulf War but was subsequently rebuilt. Today it appeared to be largely unused, even by guests. Although tables and chairs were set up in two alcoves, boxes of hot pink facial tissue on the tables were unopened. A 1970s-era Toshiba projection television and a twin-cassette boom box, neither of which looked like they had been switched on in years, were placed next to one set of chairs. Models of the palace -- before and after the bombing -- were displayed on small tables in the center of the foyer.

Despite a plain yellow-brick exterior, the inside of the building was fairly ornate. The floors were white marble, covered in places by red, green and blue rugs. Elaborate gold-and-crystal chandeliers hung from the ceiling. The two elevators had gold-plated doors.

The inspectors today might have been looking for obvious changes since 1998 or seeking to follow up possible intelligence reports about activities inside. In one inspector's vehicle, which was parked in front of the main gate to prevent Iraqi cars from exiting the compound, a black-and-white map titled "Sijood Palace Presidential Site" could be seen on the front seat. The map, which identified 19 buildings on the site, had some of the structures labeled as "blue" and "red" areas.

Journalists gather inside the foyer of the Sijood presidential palace in Baghdad after the site was inspected by U.N. weapons experts, who were allowed to enter the compound after a brief wait.A soldier stands outside the Sijood palace, one of many presidential sites to which previous U.N. inspection teams had only restricted access.