American authorities have promised rewards to Iraqis for information leading to discovery of nuclear, chemical or biological weapons programs, the U.S.-run Information Radio (search) said Saturday.

The reward announcement comes as the U.S. military teams have so far been unable to find solid evidence of Iraqi projects for weapons on mass destruction (search). The suspected presence of such weapons was the prime reason cited by the Bush administration for launching the war against Iraq.

Besides the unspecified reward, potential informants were offered anonymity and guarantees of safety in exchange for useful information "regarding any site that manufactured or held weapons of mass destruction."

"The reward you may get can improve your living standard," it said.

The lengthy spot on the Arabic-language radio was part of a growing U.S. government campaign to find Iraqi sources potentially knowledgeable about prohibited arms programs. American officials have indicated they would increasingly depend on hoped-for Iraqi informants to trace any weapons-making programs.

From November to March, U.N. weapons inspectors (search) conducted more than 700 surprise inspections at hundreds of Iraqi sites, and did not report finding any weapons-making programs. A U.S. military unit of experts in unconventional arms that followed invading U.S. troops into Iraq in March, has surveyed 75 of 90 high-priority sites, and thus far also has not reported conclusive evidence of such programs.

The difficulty in finding any banned weapons now threatens U.S. and British plans to end U.N. sanctions against Iraq. Russian diplomats have said they need to see conclusive evidence that such programs have been eliminated before approving the lifting of the 13-year sanctions regime, and President Vladimir Putin has even raised the possibility that Saddam Hussein could still be alive and in possession of the deadly weapons.

High-ranking Iraqis in U.S. custody have uniformly denied that their government, ousted last month by the invasion force, had any weapons of mass destruction, U.S. officials say.

The deposed government maintained it destroyed its chemical and biological weapons by the early 1990s. It never succeeded in building a nuclear weapon.

Saturday's radio announcement said the U.S.-British coalition was interested in "locations of components, materials and supplies that had been used in developing, processing, manufacturing and maintaining weapons of mass destruction."

Meanwhile, in the second such find this month, U.S. troops found a trailer they suspect could be a mobile biological weapons laboratory near the northern city of Mosul (search), a New York Times correspondent with the troops reported.

The trailer, stripped by looters, was located just outside the entrance of al-Kindi, Iraq's largest missile research and testing complex, according to the report posted Saturday on the Times' Web site. The trailer contained an air compressor, refrigerator, fermenter and dryer, items associated with a biological weapons lab, Maj. Paul Handelman of the 101st Airborne Division's chemical weapons team told the paper.

U.S. troops found a similar trailer in northern Iraq earlier this month, but the military has said it still has not confirmed whether it was used for biological weapons.