More than a thousand people have been evacuated as Japan battles its largest wildfire in more than three decades.

The flames are estimated to have spread over about 1,200 hectares (3,000 acres) in the forest of Ofunato in the northern region of Iwate since a fire broke out on Wednesday, according to the Fire and Disaster Management Agency.

“We’re still examining the size of the affected area, but it is the biggest since the 1992 wildfire [in Kushiro, Hokkaido],” an agency spokeperson said.

That fire burned 1,030 hectares, the previous record. About 1,700 firefighters were being mobilised from across the country, the agency said.

Aerial footage from the public broadcaster NHK showed white smoke billowing up and covering an entire mountain.

Local police found the body of one person who had been burned, while more than 1,000 nearby residents have been evacuated and more than 80 buildings had been damaged as of Friday, according to the Ofunato authorities.

The cause of the blaze remained unknown.

Two other fires were also burning on Saturday, one in Yamanashi and another elsewhere in Iwate.

There were about 1,300 wildfires across Japan in 2023, concentrated in the February to April period when the air dries out and winds pick up. The number of wildfires has declined since the peak in the 1970s, according to government data.

Ofunato has had only 2.5mm (0.1 inches) of rain in February – far below the previous record low for February of 4.4mm in 1967.

Last year was Japan’s hottest since records began, mirroring other countries as ever-rising greenhouse gas emissions fuel the climate crisis.