France has detected a "highly pathogenic" strain of bird flu at a poultry farm close to the Belgian border, the government said today.

It's the first time since an serious outbreak last winter that the avian flu has been found in a French farm, the agriculture ministry said in a statement, although four cases have been found among wildlife and three in backyard poultry.

The virus is being analysed by the French Agency for Food, Environmental and Occupational Health and Safety. All birds at the affected farm in the northwestern town of Warhem will be killed and a 10-kilometer surveillance perimeter has been set up, with all movement of poultry prohibited in the area.

Part of the circumscribed area is in the Belgian province of West Flanders. Belgium's Federal Agency for the Safety of the Food Chain today adopted additional measures for the towns of De Panne, Veurne, Alveringem and Poperinge. Poultry farmers and private owners must keep birds caged, and poultry shows and markets are prohibited.

Consumption of poultry and eggs presents no risks to humans, the French ministry said.