The biggest blazes are in southern Chubut province, where at least 45,000 hectares of forest -- an area roughly the size of San Francisco -- have gone up in smoke since mid-January.

Hundreds of firefighters are trying to prevent the flames reaching populated areas.

President Javier Milei's spokesman Manuel Adorni said a state of emergency would take effect in Chubut, Rio Negro, Neuquen and La Pampa provinces of Patagonia on Friday.

The measure is expected to facilitate cooperation between provincial and national firefighters.

Los Alerces National Park, a vast reserve of pristine forest and glacial lakes, has been among the worst-affected areas.

In the past few days, colder weather and drizzle have provided some respite for firefighters, the deputy director of the federal emergencies agency, Ignacio Cabello, told El Chubut FM radio.

"Today, the weather conditions helped," Manuel, a volunteer firefighter in the Chubut town of Cholila, which is threatened by flames, confirmed.

"We are ensuring that the fire doesn't continue to expand," the man, who did not wish to give his surname, told AFP.

Another major fire near the small Andean town of Epuyen was said by provincial authorities to be "85% contained."

The fires have been fanned by high temperatures and strong winds at the height of summer.