Updated

India's largest pharmaceutical maker lied about test results for more than two dozen of its generic drugs, U.S. regulators said Wednesday.

The Food and Drug Administration is halting any consideration of new drugs from Ranbaxy's Paonta Sahib plant, saying officials there falsified data on drugs submitted to the agency.

The action comes six months after the FDA closed U.S. borders to more than 30 generic drugs made at that plant and another Indian plant where inspectors uncovered manufacturing problems.

Regulators said they have been investigating the testing violations for years, but only recently had enough evidence to begin rejecting new drug submissions.

Federal investigators found the company did not properly test the shelf-life and other safety measures of its drugs and then lied about the results. In one instance, company officials refrigerated drugs then indicated they had been stored at room temperature. At other times the company lied about the number and frequency of safety tests conducted.

Twenty-five drugs affected by the problems likely reached the U.S., regulators said, though the September import ban means it has been months since most of the pills reached pharmacy shelves.

Three drugs tested at the Paonta Sahib plant are still in U.S. circulation because they are manufactured at the company's New Jersey plant. Those drugs are a generic decongestant and generic versions of Merck & Co. Inc.'s Zocor and Bristol-Myers Squibb's Pravachol. Both are widely used cholesterol drugs.

Those drugs likely underwent new testing when they were transferred to the U.S. for production, regulators said.

Despite the fraudulent data, regulators said they have no evidence the drugs are dangerous and recommended patients continue taking their prescriptions.

"We've not uncovered any harm associated with Ranbaxy products currently marketed in the U.S.," said FDA Deputy Director Douglas Throckmorton. "We feel comfortable leaving those products on the market at this time."

Ranbaxy has three other plants in India that import drugs to the U.S., such as low-cost versions of popular cholesterol drugs and antibiotics. The FDA said it has inspected Ranbaxy's plants more than 20 times in the past four years without uncovering similar problems. Officials did not specify how many drug applications Ranbaxy had pending review at the FDA. But the agency says it uncovered false information in those applications as well.

"Companies must provide truthful and accurate information to the FDA, and when they don't, there will be serious consequences," said Deborah Autor, director of drug compliance.

India has become one of the world's leading suppliers of generic drugs in recent years, with companies like Ranbaxy and Dr. Reddy's Laboratory able to undercut prices from U.S. competitors like Watson Pharmaceuticals.

Concerns about Ranbaxy have been growing since FDA inspectors first uncovered quality problems at one of its factories in 2006.

Calls placed to Ranbaxy's U.S. headquarters in Princeton, N.J. were not immediately returned.

FDA said it would only resume reviewing drugs from the Ranbaxy plant if the company "assures the agency of the integrity and reliability of that data." The company will have to put in place a new quality-control plan and agree to inspections by outside auditors.

Japanese drugmaker Daiichi Sankyo Co. bought a controlling stake in Ranbaxy late last year.