Investigators are working to establish the cause of the blaze, which scorched some 450 hectares of protected wetland and forest in the country’s northeast.
The fire, which ignited near the village of Kopytkowo, affected an area where Augustów and Mońki counties meet in the Podlaskie region, Polish state news agency PAP reported.
While firefighters say the situation is now under control, full extinguishing could take several days.
In some areas, the flames reached underground peat layers, making the effort more complex.
Police in the town of Augustów have launched a criminal investigation into what the penal code describes as "causing direct danger through fire to the life and health of many people or to property of large scale."
The local prosecutor’s office was expected to formally open the investigation on Wednesday.
'Every lead will be thoroughly checked'
Kinga Kalinowska, spokeswoman for Augustów police, urged anyone with information to come forward.
"All persons with knowledge about the circumstances of the fire are asked to contact their nearest police station or call the emergency number," she said. "Information can also be shared anonymously. Every lead will be thoroughly checked."
Prosecutors are particularly interested in locating people who were in the area during the Easter holiday.
"The weather was warm and pleasant, and the park is a popular destination. We hope someone who was out for an Easter walk or trip noticed something,” said Sebastian Piekarski, head of the District Prosecutor’s Office in Augustów.
He added that they are especially looking for anyone who may have seen suspicious behaviour, including individuals moving through the park’s reed beds.
Photo: Łukasz Rutkowski/State Fire Service (PSP)
This spring’s fire is the largest in the region so far this year and brings back memories of a devastating blaze five years ago in a nearby part of the park.
That fire, the worst in the park’s history, destroyed 5,300 hectares of marshland and forest.
Investigators at the time explored both intentional and accidental causes. Experts concluded that the blaze showed signs of being deliberately set in multiple locations.
Although that earlier investigation was extensive and included cash rewards offered by local officials, it was eventually closed after nine months due to a lack of suspects.
The Biebrza National Park is one of Poland’s most ecologically valuable areas, home to unique wetland habitats and numerous protected species.
Fires in such locations threaten human safety and property and can cause long-term damage to plant and animal life, reducing the natural value of protected sites.
(rt/gs)
Source: IAR, PAP