Geneva - The World Health Organization said Tuesday it was up to health authorities in individual countries to decide on the appropriate shelf life for the anti-viral Tamiflu, following a recommendation by its maker for an extension.

Swiss pharmaceutical Roche, which makes Tamiflu, known also by its generic name oseltamivir, recently showed scientific evidence that the drug could last longer than originally expected.

The European Medicines Evaluation Agency has extended the shelf life of Tamiflu capsules from 5 to 7 years, and indicated it is acceptable for this to be applied retrospectively to current stocks, in light of the pandemic swine flu outbreak.

Oseltamivir is one of the key anti-virals being used against A(H1N1), as the pandemic influenza is technically dubbed.

"It is WHO's view that shelf-life extensions are a matter for national regulatory authorities," spokesman Gregory Hartl said in an E-mail sent to reporters. (dpa)