The lethal strain has already spread from Asia to Europe

An official said it would take a number of days to determine whether the birds are carrying the strain of the avian flu that is lethal to humans.

He said evidence suggested the birds were not infected with the same virus that has affected birds in Asia.

The H5N1 strain has killed more than 60 people in South East Asia since 2003, most of them in Vietnam and Thailand.

Low threat

Thirty-three ducks in Canada tested positive for the virus, among thousands of healthy animals tested across the country.

H5N1 BIRD FLU VIRUS Principally an avian disease, first seen in humans in Hong Kong in 1997 Almost all human cases thought to be contracted from birds Possible cases of human-to-human transmission in Hong Kong, Thailand and Vietnam, but none confirmed

Q&A: Bird flu

"These findings do not indicate that we are dealing with a virus strain capable of causing significant illness," Jim Clark of the Canadian Food Inspection Agency said.

"It's important to clarify that the avian influenza virus is not new to wild birds," he added.

Tens of millions of birds have been destroyed around the world since the deadly strain of the virus was first detected in 2003.

The disease has also been detected in birds in Russia, Croatia, Turkey and Romania.

While more than 60 people have died of the virus, there is only one suspected case of the disease being passed from human to human.