The Japanese city of Utsunomiya has suspended all 94 of the primary and middle schools that it operates on Monday after its first-ever bear sighting, a municipal official said.

The city of half-a-million residents about 100 km (60 miles) north of Tokyo said the bear was first seen in a residential area near a park on Saturday evening. It remains at large after the last sighting early Monday morning about half a kilometre from a middle school.

Bear attacks, including in urban areas, have been on the rise in Japan, prompting the government to set up a task force this year to reduce casualties.

Last week, a bear attack in the northeastern city of Fukushima left at least four people injured. Security footage from Fukushima Steel Works shows a black bear chasing a worker by the entrance of the factory and throwing him to the ground.

Asiatic black bears are listed as a vulnerable species globally, but their numbers are estimated to have tripled in Japan since 2012, helped by a decline in hunting.

Experts say climate change has reduced harvests of bears' natural food like acorns and beechnuts, while the depopulation of rural areas and the proliferation of abandoned farmland have emboldened them to seek food near human settlements.