Avian influenza has been found at a third farm in western Canada and there are fears it may have spread to two more farms, officials have said.

The latest confirmed case of the disease was at a farm east of Vancouver, British Colombia that is within two kilometres of two other farms hit by bird flu earlier this month, reported Agence France Presse.

The Canadian Food Inspection Agency ordered the slaughter of a further 8,500 chickens, bringing the total number of birds slaughtered on farms in the area in recent weeks to around 60,000.

The disease found on the farm was the H7 strain, a milder form of the disease than that which has caused more than 20 human deaths in Asia.