TOKYO (Reuters) - Japan plans to keep stockpiling theTamiflu anti-viral drug to tackle any future bird flu pandemic,even though it has warned doctors not to give the drug toteenagers, a Health Ministry official said on Tuesday.

The decision on stockpiling was made at a meeting ofexperts on Monday, the official said.

Japan plans to store enough doses within the next year totreat 25 million patients and to prevent 3 million people frombeing infected with the H5N1 avian flu virus.

The virus has swept through poultry across Asia to Africaand Europe. Experts believe it could mutate into a form thatwould easily pass from one person to another, killing tens ofmillions of people within months.

The Health Ministry said last Wednesday it had ordered theimporter of the drug to warn doctors against giving it toteenagers after two new cases of abnormal behavior werereported.

Two teenagers were hurt in February and March by fallingfrom buildings after taking the drug, produced by Swiss firmRoche Holding AG, the ministry said.

A total of 15 young people have been injured or killed insimilar incidents since 2004, the ministry said last week, asconcern mounted that Tamiflu could induce psychiatric symptoms.Roche has disputed suggestions that its drug is unsafe.

The ministry was quoted by Kyodo news agency late onTuesday as saying there had been reports of 81 cases ofpsychiatric or nervous symptoms in children under 10 who hadtaken Tamiflu in the two years up to last March.

Ministry officials were not available for comment.

Tamiflu is imported into Japan, the world's heaviest userof the drug, by Chugai Pharmaceutical Co. Ltd., a Japanese drugmaker half-owned by Roche.