For the first time, the EU Commission is withholding certain financial resources for a member state because it does not comply with a ruling by the highest European court.
Brussels informed Poland on Tuesday that the EU would withhold payments from the regular transfers as compensation for the first tranche of a fine imposed by the European Court of Justice (ECJ) that the country failed to pay.
An EU representative explained that it was initially around 15 million euros.
The case is about the dispute over the Polish open-cast lignite mine in Turow near the Czech border.
The Czech Republic had sued Poland for environmental damage before the ECJ, which sentenced Poland to a daily fine of 500,000 euros in September.
According to the ECJ, Poland must end opencast mining in Turow.
The national-conservative government in Warsaw opposed this.