Police in Japan can from Thursday use rifles to shoot bears after strict gun laws were revised to help authorities battle a spate of fatal attacks.

A record 13 people have been killed by the animals across the country since April, with incidents reported on an almost daily basis of bears entering homes, roaming near schools and rampaging in supermarkets.

The government is scrambling to deal with the surge in maulings, which scientists say is being driven by a fast-growing bear population combined with this year's bad acorn harvest and a falling human population.

The northern prefectures of Akita and Iwate, where most of the attacks have taken place, held a ceremony on Thursday for riot police, who will now be allowed to use rifles to shoot bears.

Local officials confirmed to AFP that changes to gun rules had come into effect Thursday after being announced last week.

The revision came as media reports said handguns issued to regular Japanese police are of limited use against bears because the weapons are not powerful enough to kill them.

Meanwhile, the U.S. embassy in Tokyo posted on Wednesday a "wildlife alert" on its website warning people to avoid walking alone in areas where bears had been sighted or stay away altogether.

The embassy noted that local authorities closed a zoo in Sapporo in Hokkaido adjacent to the U.S. consulate general following a bear sighting in the vicinity.

"Although the Consulate is located outside of the park, we encourage all visitors for routine or other services to be diligent and aware of your surroundings," the embassy said.

The British government has also urged travelers to avoid solo walks in areas where bears have been spotted.

There have been regular sightings and attacks in recent weeks.

On Wednesday, a bear cub appeared in the vicinity of Iwate Hanamaki Airport in Iwate prefecture, causing the closure of the runway for more than an hour and the delay of two domestic flights, local official Shigeo Konno told AFP.

Japan also began deploying soldiers last week in the hard-hit Akita region, although the troops will not carry firearms or hunt the bears.