Canada has banned shipments of poultry from California because of an outbreak of Exotic Newcastle Disease, which is harmless to humans but fatal to birds. The ban will be in force for two weeks.

Mexico joins Canada in banning shipments of poultry and poultry products from California, according to the California Farm Bureau. The poultry industry in California is valued at $3 billion US and Mexico is the state's biggest export martket.

More than a million chickens have been destroyed after new cases of the disease were found this week. The outbreak came to light last September in chicken flocks in Los Angeles County.

Quarantine restrictions now apply in six California counties: Ventura, Riverside, San Bernardino, Los Angeles, San Diego and Orange. The California Poultry Federation wants the export ban confined to these six counties and not the entire state.

The ban includes live birds and poultry products, but not eggs that have been sanitized.

An outbreak of Exotic Newcastle Disease in California in the 1970s led to the destruction of 12 million chickens. For a time it threatened the entire U.S. poultry and egg supply.