Tokyo: A 4.2-foot tall bear who weighs an estimated 50 kilos attacked and killed a Japanese man who was found inside the animal's cage, police said Monday.

Neighbours heard 56-year-old Soichiro Mori screaming for help at a house northeast of Tokyo on Sunday morning, according to a police spokesman.

"When the neighbour went to the house, an injured person was found in the cage," the spokesman told AFP.

The 15-year-old Asian black bear was owned by a 70-year-old man who kept the animal in a cage in his house.

According to public broadcaster NHK, Mori was the bear's caretaker who had been hired by its owner.

Mori was rushed to hospital but pronounced dead later Sunday, the police spokesman said.

The owner, who has not been named, had an official permit to keep the bear, which is legal in Japan.