PHARMACEUTICALS group GlaxoSmithKline has won US approval of its prescription antiviral drug Relenza as a tool for preventing flu in adults and children.

Relenza joins Roche's Tamiflu as the only other drug with Food and Drug Administration (FDA) clearance for both prevention and treatment of influenza.

Countries around the world have been stockpiling both drugs for use in case the H5N1 avian flu virus changes to a form that spreads easily among people and sparks a global pandemic.

Glaxo, which is based in Middlesex, employs more than 1,000 people at its site in Barnard Castle, County Durham.