The figure cited by Rafik Baba Ahmed, former director of the El Kala Biosphere Reserve, means that the burned area of the park alone is almost double what the civil defense service said has been destroyed throughout Africa's largest country since June.
Algeria's northeast was particularly hard-hit since Wednesday by blazes exacerbated by climate change. Fierce fires have become an annual fixture in Algeria's parched forests where climate change is exacerbating a long-running drought.
But the fire service on Saturday said most of the fires there had been put out.
"The Wednesday fires damaged around 10,000 hectares (24,700 acres)" of the park, Baba Ahmed said.
According to the United Nations cultural agency UNESCO, El Kala Biosphere Reserve covers more than 76,000 hectares.
It is the last refuge of the Barbary Red Deer and "home to a very remarkable bird life, more than 60,000 migratory birds every winter," UNESCO's website says.
"It is (a) mosaic of marine, dune, lake and forest ecosystems, with its marine strip rich in corals, Posidonia meadows and fish," UNESCO says.
According to Baba Ahmed, forest covers 54,000 hectares of the park and most of the trees are cork oak.
"It is considered one of the main biodiversity reserves in the Mediterranean basin," he said, extolling its "exceptional biological richness."
Baba Ahmed said he was "very pessimistic" about the future of the area regularly damaged by forest fires.
"Over time the fires weaken the forest, making it vulnerable to other attacks: harmful insects but especially to human activities."
As a consequence, the area loses its flora and fauna, the forestry expert added.
Civil Defense Colonel Boualem Boughlef said on television Friday night that since June 1, 1,242 fires had destroyed 5,345 hectares of woodlands in Algeria.
Baba Ahmed said that figure is not realistic.
While Algeria's northeastern fires have been largely extinguished, firefighters fought two blazes on the other side of the country in Tlemcen, in the far west, the civil defense said Saturday on its Facebook page. And the fire service tweeted late Friday that fires were burning in the far northeastern regions of El Tarf and Skikda.
State television showed images of an army firefighting aircraft over El Tarf, and police said several highways in the area had been closed.
The fires led Algerians both at home and in the diaspora to collect clothing, medicines and food to help those affected. Since Wednesday, more than 1,000 families have been evacuated.
The justice ministry launched an inquiry after Interior Minister Kamel Beldjoud suggested some of this year's blazes were started deliberately, and authorities on Thursday announced four arrests of suspected arsonists.
If found guilty, they could face between 10 years and life in prison
European Union foreign policy chief Josep Borrell has also offered support, and French President Emmanuel Macron called his Algerian counterpart Abdelmadjid Tebboune to express his condolences "for the victims of the fires", state news agency APS reported on Saturday.
Spain and Portugal too fought massive wildfires over the past week, including in another UNESCO-listed park where more than 25,000 hectares were estimated to have been scorched.