Three lions have died within a week at a zoo in Tokyo, Japan, from suspected heatstroke as the country grapples with extreme temperatures.

According to officials quoted by CNN, the lions at Tama Zoological Park in western Tokyo are believed to have succumbed to heat-related complications after prolonged exposure to intense heat and humidity.

Of the 16 lions at the facility, 10 began showing signs of illness in mid-July, including loss of appetite, severe fatigue and reduced activity, prompting the zoo to suspend its lion exhibit on July 23.

The zoo confirmed that all three deceased animals were female.

Three-year-old Mugi died on July 28, 11-year-old Ichigo died three days later, and 15-year-old Luena died on Sunday, August 2.

Preliminary autopsies revealed severe dehydration and multiple organ failure, pointing to heat stress as the likely cause.

“This is the first time we’ve experienced anything like this. Last year was also hot, but none of our lions fell ill like this,” Kosaka Miwa, a representative for Tama Zoological Park, told the BBC.

A Tokyo metropolitan government official said no heat-related lion deaths had been recorded since the park began exhibiting lions in 1964.

“According to our veterinarian, the cause of the deaths is suspected to be heatstroke,” a zoo spokesperson told AFP, adding that keepers are using spot coolers, industrial fans and intravenous fluids to care for three other lions that remain in critical condition.

Japan has been experiencing unusually severe weather, with temperatures in several regions topping 40 degrees Celsius.

Authorities have issued emergency heat alerts across the country, where tens of thousands of people have been hospitalised with heat-related illnesses in recent weeks.