Weapons hunters in Iraq have found what they interpret as evidence of Iraqi preparations to secretly produce chemical and biological weapons, some Pentagon (search) officials say.

But as the postwar weapons hunt enters its sixth month, it remains unclear whether they have found — or ever will — any evidence that Iraq had actually made such weapons or whether it simply was prepared to do so.

So far, the Bush administration has not announced anything that would validate the bulk of its prewar assertions about Iraq.

"What we have not yet shown, and what really counts, was that there were major, ongoing programs at the time we invaded Iraq," said Anthony Cordesman, an Iraq expert at the Center for Strategic and International Studies (search) in Washington.

The evidence of Iraqi preparations that the teams have found so far points to plans for weapons production that was to take place primarily at "dual-use" manufacturing facilities inside Iraq, the U.S. officials said. These are buildings with an overt, legitimate purpose, such as making pesticides or pharmaceuticals, but their equipment also can be used to make weapons.

No weapons have been reported found. The officials, who spoke on the condition of anonymity, did not know whether any evidence showed that Iraq had actually produced weapons or whether it simply had plans to do so.

Last week, David Kay, the CIA (search) adviser heading up the search, told several members of Congress that he expects to find weapons of mass destruction, but that there also is the remote possibility he would not.

Defense Secretary Donald H. Rumsfeld (search), who met with Kay in Iraq on Saturday, said at a news conference in Baghdad that weapons hunters are "working diligently and professionally, and we all look forward to hearing what they have to say."

Uncovered plans and interviews with Iraqis suggested certain sites were prepared to make weapons, the defense officials said. Many of the suspect facilities themselves were looted in the chaos after the war.

Searchers have found quantities of chemicals and substances that can be used to make both weapons and legitimate civilian items, the officials said. Castor beans, for example, can be used to make brake fluid for cars and the poison ricin.

Reaching indisputable conclusions about the intended purpose of these items and sites can be difficult. Unless something else proves a particular batch of castor beans was intended for ricin production, searchers will lack solid proof of a weapons effort.

CIA officials declined to comment on any discoveries. Officials say there is no timetable for Kay to report his findings, although there has been some expectation he would provide a preliminary report this month.

Previously, the intelligence agency had publicized two discoveries in Iraq. Both have proved controversial.

As major fighting wound down, U.S. forces turned up two truck trailers that generally fit defectors' prewar descriptions of mobile biological weapons labs. Intelligence analysts at the CIA and the Defense Intelligence Agency, the CIA's counterpart at the Pentagon, said the trailers were probably indeed those labs.

But a second DIA team, composed of engineers, subsequently found the trailers were probably for hydrogen production for military weather balloons, as the Iraqis had claimed. Some State Department analysts also questioned the original CIA-DIA conclusion.

The DIA engineers said the trailers were not built to make the liquids and slurries used in biological weapons. But the intelligence analysts, citing the defectors, believe the trailers were only part of a weapons production line, arguing that other, as-yet-unfound trailers had the equipment to create a finished product.

CIA and DIA officials say the intelligence analysts stand by their findings that the trailers were for weapons.

Separately, in May, a former Iraqi nuclear scientist started providing parts and documents from Iraq's pre-1991 nuclear weapons program to CIA officers in Baghdad.

The scientist said he kept them buried in his backyard on the orders of Saddam Hussein's government, and he would dig them up to restart the program when U.N. penalties against Iraq were lifted.

The White House pointed to these as evidence Iraq still had weapons programs, although some American officials privately say they mark an intent, but not an actual program, to build a nuclear weapon.

The U.N. nuclear watchdog agency interpreted the find as proof that Iraq's nuclear weapons effort had never been revived.

Two months ago, after a visit to Iraq, Republican senators said U.S. searchers had uncovered solid evidence of weapons programs. But Democrats on the same trip said the evidence was not definitive. No one provided details.

In August, the leader of the weapons hunt, Kay, suggested a breakthrough was close. But Kay said the U.S. government would proceed slowly before going public with any discoveries, to make sure its analysis was sound.

That has left critics suggesting the administration either mishandled or exaggerated its prewar intelligence on Iraq's weapons programs.

"To date there has been no discovery that does not look like a residual or low-level effort growing out of what went on during the time before the Gulf War or when (pre-1998 U.N. inspectors) were still inspecting Iraq," Cordesman said.

He offered several possibilities:

—Without U.S. intelligence spotting them, the Iraqis destroyed their weapons programs, either in a deliberate manner in the 1990s because of the inspections, or perhaps in a panic before the recent war.

—The Iraqis hid the weapons so well that U.S. weapons hunters still cannot find them, a prospect Cordesman regarded as unlikely given the months of searching by U.N. and U.S. representatives.

—The Iraqis reduced their efforts to small-scale research programs, with plans to ramp up activities once U.N. penalties were lifted. Any production lines were never activated before the war.

—The administration has found some evidence of more widespread programs but is keeping it secret despite international pressure to justify its invasion of Iraq.