The Bush administration has assembled what it believes to be significant intelligence showing that Iraq has been actively moving and concealing banned weapons systems and related equipment from United Nations inspectors, according to informed sources.

After a lengthy debate over what and how much of the intelligence to disclose, President Bush and his national security advisers have decided to declassify some of the information and make it public, perhaps as early as next week, in an effort to garner more domestic and international support for confronting Iraqi President Saddam Hussein with military force, officials said.

"The United States possesses several pieces of information which come from the work of our intelligence that show Iraq maintains prohibited weapons," Secretary of State Colin L. Powell said in an interview published yesterday in an Italian newspaper. "Once we have made sure it can be done safely, I think that in the next week or soon after we can make public a good part of this material."

The information was gathered by U.S. intelligence agencies from what officials characterized as an array of sources and methods. The administration believes it shows that senior Iraqi officials and military officers who report to members of Hussein's inner circle have personally directed the movement and camouflage of the weapons or have knowledge of the operations, the sources said.

The concealment efforts have often taken place days or hours ahead of visits by U.N. inspection teams, which have been operating in Iraq during the past two months, according to these accounts. In many cases, the United States has what one source called "compelling" intelligence that is "unambiguous" in proving that Iraq is hiding banned weapons.

Speaking to reporters yesterday, Powell said that U.N. inspectors have picked up similar indications of Iraqi concealment and that the United States supported the inspectors' claims. "The inspectors have also told us that they have evidence that Iraq has moved or hidden items at sites just prior to inspection visits. That's what the inspectors say, not what Americans say, not what American intelligence says," he said. "Well, we certainly corroborate all of that, but this is information from the inspectors."

Administration officials have said for weeks that the United States has intelligence demonstrating that Iraq maintains banned weapons programs. But they have said they could not disclose the information because doing so would jeopardize U.S. intelligence-collection methods or military operations against possible weapon storage sites in the event of war.

The administration's decision to release even partial accounts of what it believes it has learned would clearly be designed to bolster the U.S. case in the U.N. Security Council, where leading members oppose an early decision to go to war, and among many Americans, who recent polls suggest are not convinced of the need for an immediate military confrontation. Democrats on Capitol Hill recently have increased calls on the administration to make public what it knows.

Despite the building pressure on the United States to support its claims about Iraqi behavior, sources said that U.S. intelligence agencies have not traced or located a large cache of prohibited weapons or ingredients used in the making of chemical or biological weapons. They said the U.S. government still lacks a "smoking gun" -- the kind of definitive evidence that would prove that Iraq still has chemical or biological weapons, or a nuclear weapons development program.

On top of that, what little intelligence the administration has released about Iraq has been challenged by U.N. officials and some Security Council members. In particular, these critics cite Bush's allegation, made to the U.N. General Assembly in September, that Iraq had tried to buy thousands of high-strength aluminum tubes to enrich uranium for nuclear weapons. After investigating the claim, U.N. inspectors concluded the tubes likely were never meant for enriching uranium but rather were intended as components for ordinary artillery rockets -- a finding consistent with Iraqi explanations.

A senior State Department official said the information the administration plans to release will show what the Iraqis are "doing, what they're not doing, how they're deceiving."

"We will lay out the case that we can, and we will leave it to others to judge," the official said. "When you listen to it, it should be disturbing to those people who listen objectively. To those who have made up their minds and want to duck their heads in the sand, it will pass right over them."

Spokesmen for the White House and U.S. intelligence agencies declined to comment.

In one recent example of what officials described as Iraqi obstruction, a ranking Iraqi official issued a warning that U.N. inspectors were planning a visit and directed those at the site to conceal specific prohibited weapons. In another, an Iraqi official directed scientists and others involved in research or production of chemical and biological weapons to conceal their files and papers from the inspectors.

In other cases, the sources said, the intelligence is more circumstantial. These would include photographs of intense activity around a building believed to be involved in the manufacture or storage of prohibited weapons.

Stephen J. Hadley, Bush's deputy national security adviser, heads a small task force that is trying to sort through the intelligence and recommend what to declassify. But officials said the process is complicated because revealing the exact intelligence could compromise sources and methods of intelligence gathering that would be needed in the confrontation with Iraq, particularly if it leads to war.

Contingency planning for a possible war with Iraq anticipates weeks of bombing and a ground invasion force of more than 100,000. The beginning of such a military operation would be precisely when timely intelligence would be most valuable to the U.S. military. As a result, U.S. intelligence agencies have been reluctant to jeopardize their sources and methods of collecting information in Iraq.

Staff writer Peter Slevin and researcher Mark Malseed contributed to this report.