The EU’s highest court has ruled that Poland’s logging of the ancient Białowieża forest is illegal, potentially opening the door to multi-million euro fines.

At least 10,000 trees have been felled in Białowieża, one of Europe’s last parcels of primaeval woodland, since the former Polish environment minister, Jan Szyzko tripled logging limits there in 2016.

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The government claims that the forest was bring protected from a spruce beetle outbreak were dismissed by European court of justice judges, who said that Poland’s own forest management plans showed that logging posed a greater threat to Białowieża’s integrity.

A minimum fine of €4.3m, potentially rising to €100,000 a day, could now be levied against Poland if the tree fells continue.

James Thornton, the chief executive of the green law firm ClientEarth, said: “This is a huge victory for all defenders of Białowieża forest. Hundreds of people were heavily engaged in saving this unique, ancient woodland from unthinkable destruction.”