The lawsuit alleges the companies continued distributing the blood-clotting product in Asia and Latin America in 1984 and 1985, even after they stopped selling it in the United States because of the known risk of HIV and hepatitis transmission.

The lawsuit filed Monday in federal court seeks class-action status on behalf of thousands of foreign hemophiliacs who received the product, said attorney Robert Nelson. It accuses the companies of negligence and fraudulent concealment.

"This is a worldwide tragedy," Nelson said. "Thousands of hemophiliacs have unnecessarily died from AIDS (news - web sites) and many thousands more are infected with HIV or hepatitis C."

Bayer rejected the claims, saying in a statement from its headquarters in Leverkusen, Germany Tuesday that it would examine the lawsuit and prepare its defense.

"Bayer at all times complied with all regulations in force in the relevant countries based on the amount of scientific evidence available at the time," the company said, adding that decisions made 20 years ago should not be judged by today's scientific knowledge.

Nelson said the lawsuit was filed in California because defendant Cutter Biological, now a division of Bayer, was formerly based in Berkeley. Several plasma donation sites also were located in the San Francisco Bay area, he said.

The lawsuit was filed less than two weeks after an investigation by The New York Times accused the company of selling old stock of the medicine abroad, while marketing a newer, safer product in the United States.

Bayer told Times it sold the old medicine because some customers doubted the effectiveness of a new version of the product, and because some countries were slow to approve its sale.

While the company said it acted responsibly and in line with the best medical knowledge at the time, Bayer and three other companies that made the concentrate settled 15 years of U.S. lawsuits from people who took the drug, paying about $600 million.

The medicine, called Factor VIII concentrate, can stop or prevent potentially fatal bleeding in people with hemophilia.

Early in the AIDS epidemic, the medicine was commonly made using mingled plasma from 10,000 or more donors. Because there was not yet a screening test for HIV, the virus that causes AIDS, thousands of hemophiliacs were infected.

But the lawsuit alleges Bayer and the others refused to take precautions that could have made the product safer.

As of 1992, the contaminated blood products had infected at least 5,000 hemophiliacs in Europe with HIV. More than 2,000 had already developed AIDS and 1,250 had died from the disease, the lawsuit said.

By the mid-1990s in Japan, hemophiliacs accounted for the majority of the country's 4,000 reported cases of HIV infection and virtually all infections of Japan's hemophiliacs have been linked to contaminated blood products imported from the United States, the lawsuit said.

In Latin America, at least 700 HIV cases are linked to use of contaminated blood products by hemophiliacs, the lawsuit said.