Around 200 miners have protested outside the European Commission building in Warsaw against planned coal mine closures which they say will cause unemployment and higher fuel prices.
The phase-out has been promised by the Polish government as part of efforts to combat global warming.
"Energy transformation - yes”, said Sebastian Kocwin from the All-Poland Alliance of Trade Unions. “But under fair conditions. Calmly and slowly, so that you replace every job that is about to be liquidated with a job in a related industry. Where earnings are similar, where you have similar respect and prestige. And not low-quality jobs."
More than half of Polish electricity comes from coal - and many there argue it should continue to do so.
"Poles will not agree to a drastic increase in energy prices,” said MP Janusk Kowalski from the Poland in Solidarity party. “Energy sovereignty is built on the basis of having your own resources. Poland has its own coal and we should produce energy and heat from that."
The protesters handed over a petition to the representative of the European Commission.