Three former Filipino nationals who are now U.S. citizens have filed a lawsuit demanding compensation from two Japanese companies for allegedly using them as slave labor during Japan's World War II occupation of the Philippines, their attorneys said Thursday.

According to the suit filed Wednesday at the San Francisco Superior Court, Alberto Saldajeno, 80, was forced to work in a copper mine operated by Ishihara Sangyo Kaisha Ltd. while Acelopio Galedo, 79, was forced to work on constructing a road to the mine. Generoso Jacob, 78, says in the suit he was forced to work in a coal mine operated by a predecessor organization of Taiheiyo Cement Corp.

The plaintiffs say in the suit that they were poorly fed and beaten. "By all standards, the treatment of these laborers was illegal, immoral and outrageous," their attorney Joseph W. Cotchett said.

The suit was filed under a California law passed in July 1999 that gives state courts jurisdiction to hear World War II slave-labor cases and extends filing deadlines to Dec. 31, 2010.

The law allows former slave laborers to sue Japanese and German companies as long as branches of the firms conduct business in the state.

Thousands of people could qualify as class-action members under the lawsuit, according to a statement by the plaintiffs' attorneys.

Officials from both Ishihara Sangyo and Taiheiyo Cement said they were unable to comment on the proceedings because they had not been notified that the lawsuit had been filed.