India’s largest pharmaceutical company faces a U.S. investigation into allegations that the company made weak or adulterated HIV drugs given to thousands of AIDS patients in Africa and tried to cover it up, The Wall Street Journal reports ( 7/15).

The company, Ranbaxy Inc., received millions of dollars through American contracts under the President’s Emergency Plan for AIDS Relief (PEPFAR). Investigators from the Justice Department and the Food and Drug Administration said some of the drugs were poorly made, unstable or impotent. Ranbaxy fabricated documents to cover up the substandard products, court fillings said.

Ranbaxy said in a filing in a Maryland federal court that it was cooperating with investigators and will turn over disputed documents. According to the article, company stock shares fell more than 10 percent Monday in London after it issued a statement acknowledging the U.S. probe.

In the filing, Ranbaxy acknowledged “some serious allegations concerning compliance with U.S. law,” but the filing said that, “except for issues that have been fully aired with the government, Ranbaxy knows of no evidence to support these allegations.” A company spokesman, Chuck Caprariello, declined to elaborate.