The U.S. and Asian ban on British Columbia poultry will have a minimal effect on the Canadian economy because British Columbia exports less than 10 percent of its flock, Canadian officials said Tuesday.

The U.S., Taiwan, Hong Kong and Japan banned poultry from mainland British Columbia on Monday after a duck tested positive for bird flu, and Canadian officials said Tuesday that the same strain — nonfatal to humans — has been found at a second farm in the area. They said the virus at the farms is not the strain in Southeast Asia that has been blamed for more than 60 human deaths.

A U.S. ban on Canadian cattle because of a mad cow scare cost Canada's ranching industry $5.6 billion and strained ties between the two countries. But British Columbia only exports about 6 or 7 percent of its poultry to other countries, said provincial Agriculture Minister Pat Bell.

Dr. Brian Evans, Canada's chief veterinary officer, noted that the virus found in the duck is different from the one in Asia, but acknowledged, "We're dealing in an extremely hypersensitive environment in the world."

The Canadian Food Inspection Agency killed about 56,000 birds on the farm in Chilliwack, just outside of Vancouver, as a precaution.

The H5 virus found at the farm is a low-pathogenic North American strain, unlike the deadly H5N1 strain in Asia. Federal officials have assured Canadians that the strain of the flu found in British Columbia poses no threat to human health.

Dr. Cornelius Kiley of theCanadian Food Inspection Agency says an H5 strain of the flu was found on one of four other quarantined farms. Preparations are under way to kill the birds on the farm where the latest virus was discovered.

Kiley says the second discovery revealed a low pathogenic case of the flu that causes only mild disease in birds.

He said the situation is not worsening and there's no new risk to the public.

Canada is expected to produce a report in coming days with detail on additional testing in the area of British Columbia where the diseased birds were found, and depending on the report's results, the U.S. could narrow its ban to a smaller region, said Jim Rogers, a spokesman for the U.S. Department of Agriculture.

An outbreak of bird flu in 2004 in British Columbia prompted the killing of 17 million birds.

The U.S. bans imports of poultry from any country where the high-pathogenic virus from Asia has been found. Those countries include Cambodia, Romania, China, Russia, Indonesia, South Korea, Japan, Thailand, Kazakhstan, Turkey, Laos, Vietnam and Malaysia.