Hundreds of Bulgarian coal miners and energy workers have staged a protest amid concerns for their job safety.
Buses carried protesters from across Bulgaria for the rally in the capital Sofia, where demonstrators chanted "we want jobs" as they marched to the government headquarters.
Miners have called on the Bulgarian government to guarantee their jobs amid bids by the European Union to close mines and reduce carbon emissions.
Protesters say the EU’s time frame for closing coal mining and coal extraction is too short and argue it shouldn’t come at the expense of poorer, carbon-dependent regions.
The country's two largest trade unions - who organised the protest - said they were defending Bulgaria’s energy independence.
The unions have also warned that tens of thousands of jobs are at risk if the biggest coal mines and energy plants in southeastern Bulgaria close.
Protestors have submitted a petition with 110,000 signatures to the government, demanding that they extend the operational lifetime of the coal-fired power plants.
Demonstrators also warned that a possible energy crisis this winter in the EU could lead to a social crisis because of high carbon prices.
Nearly half of the electricity in Bulgaria is produced by coal power plants, while another 35% comes from nuclear energy. The rest is covered by hydroelectric, solar, and wind generation.
The financial burden of reducing carbon emissions poses a huge challenge to Bulgaria, which has one of the lowest gross domestic product per capita rates in the EU.
Matters are further complicated given that Bulgaria's caretaker government currently has limited powers.
After meeting with caretaker Prime Minister Stefan Yanev, union leaders said the government had agreed that the closure date for the coal power plants should be after 2040.