The blaze occurred at the GRES-2 power plant with flames spreading to the roof of the building.
The fire was attended by 14 firefighters and a helicopter, as emergency crews battled to contain the inferno.
The 120-megawatt coal-fired power plant is located near the village of Ilyinskoye.
Valery Limarenko, Sakhalin’s governor, said the fire was still burning in a post to his official Telegram channel.
He said: “Fire extinguishing at the Sakhalin GRES-2 continues in Ilyinskoe Village.
“According to information from power plant specialists, the flames are intensifying and the fire moves to the roof.
“Firemen are working on the site. 14 persons and 5 vehicles are engaged in putting out the fire.”
More to follow…..