WARSAW — Poland broke international law by drastically increasing logging in one of Europe’s last primeval woodlands, which is home to endangered animal species, an official of the European Court of Justice said on Tuesday.

Yves Bot, an advocate general at the court, issued his opinion on the Bialowieza Forest at a time of strained relations between the European Union and Poland, a member state that has repeatedly defied the organization and challenged its authority. The case will be decided by the Court of Justice, which usually follows the advice of its advocates general.

The increased logging is “necessarily liable to result in a deterioration of the breeding sites of the protected species,” Mr. Bot wrote.

In 2016, Poland said it would triple the amount of logging allowed in the Bialowieza Forest. Last year, the European Commission, the European Union’s executive body, sued in the Court of Justice to block that increase, and the court ordered Poland to halt the large-scale felling of trees until the case was resolved.