United States and European regulators have launched an investigation into the safety of Tamiflu after the deaths of 12 Japanese children who took the anti-flu drug, the Swiss official website swissinfo reported Friday.

But both US and European officials warned that it was difficult to tell whether the drug manufactured by the Swiss pharmaceutical giant Roche had played a role in the fatalities.

Tamiflu, invented by the US company Gilead and licensed to Roche in 1996, has proven effective against influenza A and B and H5N1 bird flu virus, which is threatening the world.

The US Food and Drug Administration (FDA) said the 12 deaths under investigation included one suicide, four cases of sudden death and four cases of cardiac arrest. There were also cases of pneumonia, asphyxiation and acute pancreatitis.

"The level of detail in these reports was highly variable and determining the contribution of Tamiflu to the deaths was difficult," the FDA said.

"At this point in time, we cannot make an association between Tamiflu and the deaths of these children," said FDA official Murray Lumpkin.

The FDA added that it was concerned that 32 psychiatric events, such as hallucinations and abnormal behavior, had also been reported in children who took Tamiflu.

The "most alarming" psychiatric events, according to the FDA, included two cases in which a 12-year-old and a 13-year-old jumped out of second-floor windows of their homes after receiving two doses of Tamiflu.

The FDA's European counterpart, the European Medicines Agency (EMEA), said it was also studying the possible side effects of Tamiflu.

There have been two cases of "presumed suicide associated with the medication," the EMEA said.

Interest in Tamiflu has arisen as experts around the world warn of the possibility of an H5N1 bird flu pandemic among humans. Several countries are stockpiling Tamiflu, which may be able to lessen symptoms.

This week Roche reported two possible suicide cases of Japanese teenagers who took Tamiflu but said there was no clear evidence that the drug had played a part in the deaths.

Source: Xinhua