Brussels warns Warsaw over ancient forest
The European Court of Justice in 2018 said Poland's government broke the law by allowing logging in the Bialowieza Forest, a UNESCO world heritage site.
The logging began in May 2016 and the European Commission took Poland to court arguing that it was destroying a forest that boasts unique plant and animal life.
The commission said Poland had "still not fully complied" with the court ruling, notably by failing to repeal and replace the regulations that allowed for the logging.
"Despite meetings and exchanges at technical level, at which the commission has expressed its concerns and offered advice on the correct implementation of the judgement, the situation in Poland has not changed."
The EU executive said Warsaw had two months to comply, after which Brussels would refer the case back to the court "with proposed financial sanctions".
Bialowieza, which straddles the border with Belarus, includes one of the largest surviving parts of the primeval forest that covered the European plain 10,000 years ago.
Its vast woodland is home to hundreds of European bison, the continent's largest land mammal.
The government of the Law and Justice party (PiS) had argued it was clearing dead trees to contain damage caused by a spruce bark beetle infestation, as well as to fight the risk of forest fires and preserve road traffic.
But the EU judges found that the Polish government failed to carry out "an appropriate assessment" of the impact of its forest management plan.
The court also found that the Polish plan failed to comply with EU obligations protecting nests, eggs and breeding places of bird species living in the forest.