Poland on Tuesday began a logging project aimed at protecting the Bialowieza forest, which includes some of Europe's last primeval woodland, despite protests from environmental groups, scientists and the EU.
National forest director Konrad Tomaszewski said the goal was "to stop forest degradation" by combating what the environment ministry says is a spruce bark beetle infestation.
But several environmental groups including Greenpeace have taken issue with the government's rationale, saying the beetle's presence does not pose any threat to the forest's ecosystem.
"The minister does not understand that this insect is a frequent and natural visitor, that it has always existed and the forest has managed to survive," said Greenpeace Poland activist Katarzyna Jagiello.
Bialowieza, one of the last vestiges of the immense forest that once stretched across Europe, now covers some 150,000 hectares (around 370,650 acres) in Poland and Belarus.
It is home to 20,000 animal species, including 250 types of bird and hundreds of European bison, the continent's largest mammal.
In Belarus the entire forest is protected as a nature park, but only part of the Polish section is protected.
Europe's tallest trees, firs towering 50 metres (160 feet) high, and oaks and ashes of 40 metres, also flourish in an ecosystem unspoiled for more than 10,000 years.
The government has vowed that logging would not happen in the protected areas of the forest, which was designated a UNESCO World Heritage site in 1979.
Tomaszewski told reporters that as well as safeguarding the forest, the operation launched on Tuesday will also protect tourists and rangers from harm by cutting down trees that risk falling on trails.
The environment ministry previously said loggers will harvest more than 180,000 cubic metres (6.4 million cubic feet) of wood from non-protected areas of the forest over a decade.
Tomaszewski said forest management would refrain from logging in two "reference areas" to allow "nature to fend for itself", as the environmental groups claim it is capable of doing.
Environment Minister Jan Szyszko, who was also at the press conference, said he had spoken at the European Parliament for eight hours on Monday about the project that has raised questions abroad.
A delegation from UNESCO is due to visit Bialowieza between June 4 and 8 to examine the situation.
Explore further: Greenpeace protests Polish logging of Europe's last primeval forest