The U.S. Food and Drug Administration today refuted statements by Mylan Inc., saying its investigation of the Cecil generic drug maker continues and that "statements to the contrary are untrue."

The agency released a statement two hours after Mylan issued a statement saying the FDA had visited Mylan's Morgantown, W.Va., plant yesterday and that the "agency agreed that this was a minor standard operating procedures deviation" and that "all corrective actions were fully implemented."

The FDA said yesterday it had launched an investigation into the matter. Today, FDA assistant commissioner Steven Solomon said in a statement that the agency's probe "involves allegations of compliance violations that the FDA takes very seriously."

"The investigation is ongoing and the agency has formed no conclusions at this time. Statements to the contrary are untrue," Mr. Solomon said.

A story published by the Pittsburgh Post-Gazette Sunday cited a Mylan internal report that stated workers routinely overrode computer-generated warnings about potential problems with the medications they were making. The report did not say what drugs were involved.

Mylan's report said the problem was "pervasive" and occurred on all three shifts at the plant, which makes an estimated 19 billion doses annually. It did not say how long the unauthorized practice had been going on.

The breach in quality was "very serious," involving "falsifying information" and "altering product" but did not affect the quality of the medications, the report stated. The report did not say how the company determined that quality was not compromised.

In his statement this morning, Mylan CEO Robert Coury said: "I want to first thank the FDA for responding as quickly as it did in light of the seriousness of these unfounded accusations."

"As far as the abnormal trading volume in our stock yesterday, the only thing I have to say is that there is no one in a better position to speak about these issues for a company than the standing fiduciaries, whether it is the senior management of the company or any regulatory agency," he said.

"I would hope that the market and our stakeholders take note of this."