The EU's top court on Monday ordered Poland to pay Brussels a daily fine of 500,000 euros for failing to shut a massive coal mine that angered neighbouring Czech Republic. 

Warsaw was told by the court in May to suspend extraction of lignite -- a low-quality brown coal -- at the Turow open-cast mine after a complaint by Prague that it created a cross-border environmental hazard and breached EU law. 

But the Polish government refused to comply, arguing that it would put the country's energy security "at risk" as the mine fuels a power station providing around seven percent of its electricity. 

In June, Prague asked the European Union's Court of Justice to fine Poland five million euros ($5.9 million) per day for failing to halt production at the mine. 

The governments of both countries also started official talks on the situation, vowing to strike a deal.

Both Germany and the Czech Republic have complained about the mine and its planned expansion, saying that it has also caused increased noise and dust levels in the area.

But Poland's largest energy group PGE, which owns both the mine and the plant, is planning to extract coal at Turow until 2044.

Operating since 1904, the mine employs some 4,000 people.

Poland relies on coal to meet up to 80 percent of its energy needs, but has vowed to develop green energy sources and to shut its last mine by 2049, in line with targets for emissions cuts set by the European Union.