More than a hundred firefighters are battling to control a forest fire in Chubut province, in southern Argentina.
The blaze broke out on Thursday at Los Alerces national park, a Unesco World Heritage site in northern Patagonia, which is home to huge alerce trees.
Chubut Governor Ignacio Torres blamed arsonists for the fire, which has burned more than 1,000 hectares.
He said that limited visibility caused by the smoke was hindering the work of aerial firefighters.
The fire spread as the region was experiencing an unusual heatwave which saw temperatures rise to 40C (104F) in the port city of San Antonio Oeste.
Mario Cárdenas, the fire chief at Los Alerces, said the flames had spread from the park into the neighbouring areas.
He said the fire continued to be “out of control” but that additional firefighters were expected to join the existing team.
Los Alerces national park is home to the trees of the same name which are among the longest-living in the world and can grow to a height of 45m (150ft) or more.
The park covers an area of almost 260,000 hectares and is considered key for the protection of the Patagonian Forest.
Park Director Danilo Hernández Otaño said the blaze had started at two separate but nearby locations.
Mr Hernández also said that it had been “clearly intentionally” laid and had not been an accident.
“Those responsible for starting the fire will have to answer to the courts,” Chubut Governor Ignacio Torres said.