Federal health advisers are investigating the deaths of 12 Japanese children who took Tamiflu, as well as seven other drugs.

No deaths have yet been attributed to Tamiflu in the U.S. or Europe.

"Based on the information we have right now, we cannot say definitively there is a causal relation between the drug and the children's death," Dr. Murray Lumpkin, the deputy commissioner of the U.S. Food and Drug Administration, said Thursday.

An update made by FDA staff includes reports of 32 "neuropsychiatric events" associated with the use of Tamiflu. All of which, except for one, were experienced by Japanese patients. These cases include delirium, hallucinations, convulsions and encephalitis.

While the FDA has sought, and received, more information from the makers of Tamiflu, Roche Holding AG, it has not issued any warnings or initiated other such actions.

Last week, the Japanese Health Ministry warned Tamiflu could induce odd behavior, after two teenage boys died shortly after taking the medicine.