Frank Dillman, a former prisoner of war, remembers the frigid conditions. "It was very, very cold" in the copper mine in Japan where the captured American Marine was forced to work during World War II. "There was very little food . . . terrible conditions. . . . They gave us straw shoes to walk in the snow. You just couldn't believe people could act like that."

The San Diego veteran, now 81, has sued the Japanese company he says treated him like a slave. But U.S. Ambassador Thomas S. Foley today joined the Japanese government in rejecting the claims of Dillman and thousands of other World War II prisoners who were forced to perform hard labor for Japanese companies.

Foley said the claims--among a spate of suits filed in California over wartime forced labor--are barred by the peace treaty that formally ended the war. "The peace treaty put aside all claims against Japan," Foley said in response to questions at a speech in Tokyo.

His remarks echoed statements issued this week by the Japanese Foreign Ministry, reflecting a growing dismay here over more than a dozen lawsuits filed by lawyers for American veterans after a 1999 California law extended the deadline for such actions. Lawyers said they expect the suits will be joined by thousands of ex-GIs who were forced to labor under brutal conditions for Japanese firms. The veterans say they should be compensated by the surviving Japanese companies, regardless of the peace treaty.

None of the lawsuits has been resolved, but they could cost Japanese companies operating in California large sums. Similar suits brought against German companies from the Nazi era resulted last month in the establishment of a $5.2 billion fund for compensation of wartime laborers.

The suits are generating a backlash here against what the Japanese see as an old, dead issue. If Americans press such claims, "What about the atomic bomb?" grumbled Tokyo Gov. Shintaro Ishihara on a television news program Sunday.

"If one side starts an argument that the peace treaty does not apply, then this logic should be applied to both sides," said Meisei University Prof. Keiichiro Kobori. "That means Japanese civilians have a right to ask for compensation for the bombing of more than 60 cities, killing unarmed civilians, not to mention Nagasaki and Hiroshima," targets of the 1945 atomic bombs that ended the war in the Pacific.

Foley's comments seemed to be an attempt to head off such sentiment. "I don't see any risk of inflammation of U.S.-Japan relations," he insisted. But he stressed his view that the formal peace treaty, signed in San Francisco in 1951, "put aside all claims against Japan . . . and on the other hand confiscated Japanese assets to satisfy those claims.

"No one disputes there was grave suffering in World War II, but the peace treaty does have this specific provision. . . . It is very explicit," he said.

"World War II is over. This is not a claim against Japan in any way, shape or form. This is a claim based on the conduct of certain companies," lawyer David Casey responded by phone from San Diego. "These companies engaged in highly illegal conduct and slave labor, which is in violation of all international law."

Japan routinely put men and women captured during the war to work. That work, often carried out under dire conditions for companies that the veterans say survived the war, freed Japanese manpower for military service.

Harold Poole, 81, was in the Army Air Corps when he was captured in the Philippines. He survived the Bataan Death March and was eventually shipped to Japan and put to work in a steel mill, where he toiled from 1943 to 1945.

"It was mostly hard labor," he said by phone from his home in Salt Lake City. "We had to load fuel. We got a day off once a month. We weren't getting much food--just rice, and not enough of that. There was no medical coverage. It was forced labor." He has sued Nippon Steel Corp., which he said owned the mill.

"I'm not looking for some great amount of money," he said. "My motives are to see justice served and getting the word out to the world. If it happens again, maybe they will treat POWs better than before."

Dillman, who worked in a mine in northern Japan in the last year of the war, filed suit against Mitsubishi Corp. "It had nothing to do with the military. We were civilian 'employees,' " he said. "Mitsubishi isn't going to get out scot-free. They are going to be paying somewhere along the line."

"One does wonder why all this is taking place some 50 years after the war," said Sadaaki Numata, the Foreign Ministry spokesman. "All claims from World War II, including claims of the nationals of the United States arising from actions taken by Japan and its nationals, have already been settled."

"You sign peace treaties so those kinds of issues are put to rest," agreed Jim Parkinson, a California attorney for the veterans. "But when you have private corporations that profited from the enslavement of victims of war, that's entirely different. They have an obligation to pay for what they did, and the advantage they took of these men."

Yasuaki Onuma, a professor of international law at Tokyo University, said the legal issue can be interpreted differently. But he added: "It's very unfortunate that the matter has come to court. From a moral perspective, especially after we became an economic superpower, we could have and should have [passed] the domestic law to respond to the voices of the victims."

But Onuma also decried "the tendency of the U.S. to settle every matter in a U.S. court and try to impose the effect of that decision globally. It has a self-righteous look. What will be the effect when there are claims from Vietnamese or from Latin American countries who suffered from intervention by the United States? As a human rights activist, I personally understand the feelings of the victims. But as a lawyer, I see dangers."