Japan's Environment Ministry has raised the nation's bird flu alert to the highest level after a highly pathogenic strain of the avian flu virus was detected in two towns in Hokkaido Prefecture, northern Japan.

The ministry says the bird flu virus was detected in a dead wild falcon found in the town of Otobe on September 30 and also in the droppings of wild ducks in the town of Betsukai on October 8.

The ministry set the alert to the highest level of three on Tuesday. Officials are calling on local governments across the country to strengthen the monitoring of wild birds and to step up their efforts to confirm whether those birds are carrying the virus or not.

The ministry says the bird flu viruses are not generally thought to infect humans unless they come into excessive contact with infected birds.

Ministry officials are calling on people to wash their hands and gargle if they touch bird droppings. They are also asking people not to touch dead wild birds and to inform local authorities if they find one.