Massive wildfires have ravaged Poland's largest nature reserve, the Biebrza National Park, as the country faces its worst drought in years.

After the first flames struck Sunday, the blaze spread across 6,000 hectares or 10 percent of the park, which features some of Europe's best preserved wetlands and is home to moose, beavers, wolves and unique birds.

"It's a great tragedy... Usually at this time of year, everything here is under water. I spoke to a firefighter who said they've never dealt with anything like this before," local resident Joanna Skrzypkowska told AFP.

"They're fighting really hard... they didn't sleep for three nights, just battled the fires, before help arrived," said the 56-year-old teacher, ecologist and farmer from the village of Wolka Piaseczna.