A zookeeper has died after being mauled by a rare white tiger inside its enclosure at a zoo in south-west Japan.

Akira Furusho was pronounced dead on arrival at hospital on Monday night after apparently being attacked by one of four white tigers kept at Hirakawa zoological park in the city of Kagoshima

The 40-year-old was found collapsed and bleeding from the neck by a colleague inside the tigers’ enclosure just after the zoo had closed for the day, according to Kyodo News.

The tiger thought to have been responsible for the attack had been sedated with a tranquiliser gun by the time rescue workers and police arrived. There was no immediate word on its condition. The victim’s family has asked that it be kept alive.

Police launched an investigation into how white tigers are looked after at the publicly run zoo, which opened in 1972.

“We plan not to kill Riku and continue to keep it because the bereaved family asked us to do so,” Takuro Nagasako, a zoo official, told AFP. While the zoo was open as normal on Tuesday, the white tiger observation zone was restricted “as police continued to investigate the case,” Nagasako added.

The attack on Furusho was the second involving a zoo employee in Japan this year.

In March a female worker at Ueno Zoo in Tokyo was injured when a gorilla bit her right arm. The attack occurred while she was escorting the gorilla from its public display area into its living space, reports said, prompting an investigation into how she and the animal had come into such close contact.

Rosa King, a zookeeper at Hamerton zoo park in Cambridgeshire, England, was killed in May 2017 after a tiger entered the enclosure where she was working, in what zoo officials described a “freak accident”.

After King’s death the TV presenter and naturalist Steve Backshall said that as animals that live and hunt alone in the wild, tigers kept in captivity could be exposed to unnecessary stress.

“In the wild, they’ll have enormous home ranges and rarely come into contact with other tigers,” Backshall told the BBC. “And in captivity, quite often they’ll be kept in relatively small enclosures with other tigers, and there’s no doubt that could cause artificial stresses within those enclosed populations.

“A wild tiger could range over 1,500 square miles (3,885 sq km) – obviously you could never have a zoo that size.”