A U.S. health official last month called for French drugmaker Sanofi-Aventis to halt clinical trials of its antibiotic Ketek in children because the drug could be deadly, a newspaper reported on Thursday.

The Food and Drug Administration confirmed that memos had been sent to other officials at the agency but called them “a preliminary, raw assessment,” The New York Times reported.

A final decision would be made by experts who have the full benefit of a large section of opinion and scientific fact, an FDA spokeswoman told the NYT, which obtained a copy of one of the memos.

Sanofi-Aventis also said the notes were preliminary but declined to elaborate. “We are in talks with the FDA about the side-effects of Ketek. I cannot say more,” a spokesman said.

Ketek is being tested as a treatment for ear infections and tonsillitis in nearly 4,000 infants and children in more than a dozen countries, including the United States, postings on a government Web site show.

The treatment was approved in 2004 for respiratory infections after the FDA rejected it in 2001 and 2003, asking for more safety information.

Ketek drew renewed scrutiny in January when researchers reported that three patients using it developed severe liver damage and one died.

At the request of Europe’s drug regulator that month, Sanofi included stronger warnings about potential liver disorders on product information for Ketek. The Sanofi spokesman said Ketek “in very rare cases ... could have a serious adverse reaction”.

BALANCING THE RISK

News of the memos comes after the FDA said in May that it and Sanofi were discussing possible revisions to prescription instructions for Ketek. Safety reviewers said a strong warning may be needed about cases of liver failure, the FDA said.

“How does one justify balancing the risk of fatal liver failure against one day less of ear pain?” Dr. Rosemary Johann-Liang, an official in the Office of Drug Safety at the FDA, wrote in one of the memos, the NYT said.

The parents of child patients in the Ketek trials must be better informed about its risks “in order for any of these trials to continue to proceed,” she said.

Sanofi-Aventis shares in Paris fell 1.5 percent to 71.25 euros by 1157 GMT, while the DJ Stoxx European healthcare index lost 1.4 percent.