The slaughter of up to 60,000 turkeys will likely begin at a commercial farm in B.C.'s Fraser Valley on Monday after tests showed some of the birds were infected with the H5 avian flu virus.

The Canadian Food Inspection Agency confirmed Saturday that initial tests found a "low pathogenic" level of the virus at the farm near Abbotsford, about 75 kilometres southeast of Vancouver. Pathogenicity refers to the relative harmfulness of the virus.

Additional tests are underway to determine the exact strain. The tests were conducted after some of the turkeys at E&H Farms showed signs of respiratory distress.

On Sunday, CFIA officials were preparing to euthanize the birds by sealing the barns and flooding them with carbon dioxide. Workers will then mix the carcasses with organic material in the barn to raise the temperature as high as 50 C during decomposition.

"That heating process is what inactivates the virus," Sandra Stephens, a CFIA veterinary program specialist, told the Canadian Press in an interview.

Once the birds are euthanized and disposed of, CFIA will oversee the cleaning and disinfection of the farm's barns, vehicles and equipment.

The federal agency is also extending a quarantine to 23 other farms within a three-kilometre radius.

About 17 million birds were slaughtered in the Fraser Valley in February 2004 following an outbreak of the H7N3 strain of the disease, but it was a different strain from the deadly H5N1 version linked to nearly 250 deaths and other illnesses in Southeast Asia, China, Russia and Europe.

Any infected meat that may have been sold will pose no risk to humans if the poultry is handled and prepared properly, said a disease control specialist with the CFIA. Avian influenza rarely affects humans, unless they have close contact with infected birds.

With files from the Canadian Press