BAGHDAD, Iraq, Jan. 16 -- U.N. weapons inspectors searching a large ammunition dump in the Iraqi desert today discovered a cache of 11 empty chemical warheads that were not listed in Iraq's final weapons declaration in December, U.N. officials said.

The inspectors found 12 warheads, equipped to deliver chemical agents, in "excellent condition," 11 of them empty and one requiring further testing, a U.N. spokesman said. They were discovered at an army munitions depot about 100 miles south of Baghdad, where the inspectors had gone to examine bunkers constructed in the late 1990s, he added.

Although it involved only a small number of warheads for 122mm rockets, the finding appeared to place Iraq in technical violation of Security Council resolutions barring it from possessing or developing nuclear, chemical or biological weapons. But the Bush administration's initial reaction was muted, and officials in Washington did not jump on the discovery to reinforce their repeated argument that President Saddam Hussein has been unwilling to relinquish weapons of mass destruction and must be made to do so by force, if necessary.

"This was an important discovery," a U.N. official involved in the inspections said. "This was clearly something they should not have had." But he added that the discovery was not immediately regarded by inspection leaders as "a smoking gun that proves conclusively Iraq is hiding" or producing chemical weapons.

A senior Iraqi official also played down the importance of today's find, saying his government forgot to mention the warheads in its declaration to the Security Council in December. That document was supposed to provide a final and complete accounting of Iraq's arms stockpile.

The official, Gen. Hussam Mohammed Amin, head of Iraq's weapons-monitoring directorate and the chief liaison to U.N. inspectors, said the chemical shells were overlooked because they were stored in boxes similar to those for conventional 122mm rocket warheads.

"Nobody opened this box," Amin said at a news conference convened less than an hour after the inspectors announced their discovery. "There was no intention to keep them."

Amin said the warheads, which he said were imported in 1986, were too old to be used. "It doesn't represent anything," he said. "It's not dangerous."

Under Security Council resolutions and the cease-fire agreement ending the 1991 Persian Gulf War, Iraq is forbidden to possess chemical, biological or nuclear weapons and delivery systems. Iraq has repeatedly insisted that it no longer possesses any weapons of mass destruction, saying all the chemical and biological arms it produced in the 1980s were destroyed either independently or by earlier groups of U.N. inspectors.

The U.S. government has started in the past week to provide the inspectors with additional intelligence to guide their searches, but today's finding appeared to be unrelated to that information. In a statement, the U.N. Monitoring, Inspection and Verification Commission said its inspectors traveled to the Ukhaider Ammunition Storage Area to inspect a large group of bunkers built in the late 1990s. The inspectors had noticed the bunkers when they visited the site Jan. 7 as part of their strategy to scrutinize changes at facilities that have long been associated with Iraq's weapons programs and that were visited by teams of inspectors in the 1990s.

Iraq has acknowledged acquiring a large amount of the type of chemical shells that were identified today; its military used chemical weapons a number of times during the 1980-88 war with Iran. But the warheads, which have corrosion-proof plastic liners and other features that are specific to chemical munitions, were technically banned by resolutions issued by the Security Council after the 1991 Gulf War.

After identifying the warheads, which were stored in an older section of the compound, the inspectors used portable X-ray equipment to conduct a preliminary analysis of one of them, U.N. spokesman Hiro Ueki said in a statement. The inspectors also collected samples for chemical testing, he said.

It is highly unusual for the U.N. team to announce the results of an inspection. Since it began visiting sites in Iraq on Nov. 27, officials generally have released only bare-bones information about places they have searched, refraining from mentioning whether any substantive evidence was uncovered. Ueki said he was told to disclose the discovery by his superiors.

The Bush administration has been pressuring the chief U.N. inspector, Hans Blix, to intensify the probe by conducting more intrusive searches and taking Iraqi scientists outside the country for questioning. President Bush's national security adviser, Condoleezza Rice, traveled to U.N. headquarters in New York on Tuesday to urge Blix to heed the U.S. requests.

Blix, who is scheduled to deliver a progress report to the Security Council on Jan. 27, told the council last week that the inspectors had not yet found a "smoking gun." The Bush administration, which is deploying tens of thousands of additional troops to the Persian Gulf region to be ready for a war, has made no secret of its hope that Blix's next report will provide clearer evidence of Iraqi obstruction and noncompliance.

In that light, Amin, the Iraqi weapons-monitoring chief, accused the U.N. inspection commission of distorting the significance of the warheads in response to U.S. pressure, saying he was "astonished" that it had made an announcement.

"You can't imagine the American pressure on this commission, how they want to make this finding a huge finding which is related to the mass destruction weapons -- chemical or biological," he said. "It is neither chemical, neither biological. It is empty warheads. It is small artillery rockets. It is expired rockets and they were forgotten without any intention to use them."

He accused the inspectors and the United States of "looking for a pretext to declare [war] against Iraq."

"It's all about political goals," he said.

As one team of inspectors was searching the munitions depot, another descended on the homes of two nuclear scientists to conduct unannounced interviews, intensifying their efforts to debrief people believed to be connected to past or current weapons programs.

The inspectors arrived at 9 a.m. at the Baghdad homes of a physicist, Faleh Hassan, and his next-door neighbor, Shaker Jibouri, a nuclear scientist. The U.N. personnel had to wait in the street for almost an hour while both men were summoned back from their offices. Once they returned, inspectors questioned both men in their homes and searched the premises. The scientists insisted on having Iraqi officials present.

Journalists observed the arms experts poring over documents at a table set up near Hassan's front door.

After almost six hours, Hassan, the director of a military installation that specializes in laser development, left his house carrying a box of documents and got into a U.N. vehicle with an Iraqi official and two inspectors. The group then drove to a field outside Baghdad where they briefly surveyed the grounds and inspected a small dirt mound.

Iraqi officials said the site was a farm that Hassan sold in 1996. The group then proceeded to U.N. offices here, where they photocopied the documents Hassan was carrying.

Before leaving, the chief U.N. field inspector, Demetrius Perricos, engaged in an unusually animated discussion with the Iraqi officials who accompany the inspectors. It was not clear what the men were talking about, but a reporter said he overheard Perricos saying loudly: "I'm not happy about all of this."

Amin said the inspectors also asked two other Iraqi scientists to come to the U.N. offices for an interview. He said the scientists refused to be interviewed there and demanded that Iraqi officials be present during the questioning.

The issue of interviewing weapons scientists has emerged as a key point of controversy among Iraq, the inspectors and the United States. Blix wants his inspectors to be able, at the very least, to question the scientists in private. The Bush administration wants the inspectors to go even further and take key scientists and their families out of Iraq, saying debriefing sessions in another country would allow them to provide more candid disclosures.

Iraqi officials have said scientists are free to choose whether they want to leave, but the officials have said no one wants to go. U.S. officials have depicted that as tantamount to pressuring the scientists not to go.

Hussein's chief science adviser, Gen. Amir Saadi, denied that scientists were being told what to do. "They're aware what's going on," he said. "They're aware of the purpose behind such insistences."

After the inspectors' visit, a visibly angry Jibouri called the search of his house -- which he said included bedrooms, bathrooms and his study -- "provocative and intrusive."

"They searched everything," he growled. "This is . . . police work."

Saadi sought to put the best spin on things, expressing hope that inspections would continue after Jan. 27 so Iraq's claim that it has no banned weapons can be verified.