U.N. Sifts New Iraqi Documents on Arms : Mideast: Chief inspector believes Baghdad is no longer a major threat to Persian Gulf region. But U.S. officials fear latest revelations are more lies.

U.N. officials began the daunting task Wednesday of tracking down far-flung pieces of Iraq’s non-conventional weapons complex, detailed in a trove of previously hidden government documents, as Clinton Administration officials warned that more dangers still might be discovered.

Iraqi President Saddam Hussein’s regime, which revealed the existence of biological agents and other non-conventional weapons after the Aug. 8 defection of its top arms procurer, has claimed that all of the materiel was destroyed.

But American and U.N. officials said Baghdad still possesses centrifuges that can be used to produce enriched uranium for nuclear weapons. And Hussein’s regime could have other items hidden away.

Meanwhile, there is significant disagreement between the United States and the United Nations over the significance of the Iraqi disclosures and the extent to which Hussein’s government undermines international stability.

U.N. Special Commissioner Rolf Ekeus, speaking in Amman, Jordan, where he met with Iraq’s onetime top arms procurer and a second high-level Iraqi defector, said he believes that Iraq no longer constitutes a major threat to the oil-rich Persian Gulf region, particularly in terms of chemical weapons and long-range missile capability.

Once he completes the process of verifying Baghdad’s latest accounts, Ekeus suggested, the U.N. Security Council will have “no choice” but to consider lifting international economic sanctions that have devastated Iraq’s economy.

Baghdad has demonstrated a “180-degree change in attitude,” he said. Iraqi leaders have pledged total cooperation in implementing U.N. cease-fire resolutions, although Ekeus conceded that he could not take their comments at face value since Iraq has misled the outside world for more than four years.

Senior U.S. officials said they fear Baghdad’s latest admissions are only a new generation of lies that could hide as yet undiscovered weapons capabilities. The Administration is hardening its position on attempts by key allies, including France and Russia, to lift punitive economic sanctions--the only major weapon left in the political battle to undermine Hussein’s rule.

The debate over easing sanctions so Iraq can resume selling its oil on international markets is widely expected to begin in the Security Council this fall. But Washington’s warnings about Iraqi duplicity now have greater credibility--and leverage. And U.S. officials said they think that Iraq’s revelations will delay the debate at least until spring.

The drama created by the defection of Lt. Gen. Hussein Kamel Majid, a son-in-law and former key aide to the Iraqi leader, now shifts to some of the most challenging detective work that the U.N. team has faced in unraveling the scope of Iraq’s deadly arsenal. It may take months just to sort through the dozens of boxes of data handed over last weekend, said Charles Duelfer, deputy chairman of the U.N. Special Commission. The contents of the boxes are under review by U.N. teams in Baghdad.

Most of the material involves biological weapons, but initial samplings indicate that it also includes information on nuclear and chemical weapons and missiles.

Identifying and verifying the destruction of more than 140,000 gallons of biological agents, for example, will require weeks of detective work and possibly more personnel, Duelfer said.

Weapons inspectors will be required to perform tasks ranging from sifting through samples of earth to locating barrels used to transport ingredients, many of which were purchased abroad.

Meanwhile, the first 400 of 1,400 U.S. troops arrived in Kuwait on Wednesday for a new round of war games. The exercises, which will include Marines from Camp Pendleton and members of the 1st Cavalry Division at Ft. Hood, Tex., were advanced after the defections.

The United States is beefing up its presence in the Gulf and in Jordan as a precaution against Iraqi provocation. U.S. officials have reported suspicious Iraqi troop movements, although the Pentagon has now backed away from claims last week that Hussein might have been planning to attack his neighbors.

The war exercises are the latest in a series of semiannual maneuvers conducted by the United States and Kuwait in the aftermath of Iraq’s 1990 invasion of its neighbor.

U.S. troops also are conducting two-week maneuvers in Jordan.