Petrol and diesel will cost 15 to 17 euro cents more a litre from the start of 2027 because of new EU climate rules, Svetoslav Benchev, head of the Bulgarian Petroleum and Gas Association (BPGA), told reporters.

Bulgaria, Greece, Romania, the Czech Republic, Poland and Slovakia will sign a joint declaration to the European Commission in Sofia on Thursday. The six countries want the Commission to review the climate rules for fuels and delay the start of the second part of the scheme by two years.

The scheme is the EU's second emissions trading system. It starts next year and also covers fuels. For every tonne of diesel they put on the market, producers will have to hold 3 tonnes of carbon allowances. An allowance costs €43 a tonne of CO2, before VAT and excise duty, and the price stays fixed for the next two years. This adds €150 a tonne.

If the EU also bans additives that save energy in fossil fuels, the price will rise by about another 15 euro cents a litre.

To avoid a sharp jump in prices, the government is considering a fee of 2 euro cents on every litre of fuel sold from next year. The money would go to the Decarbonisation Fund.

The industry says the new rules could cut oil refining capacity in Europe and put supplies at risk.

Another problem for business is an EU directive that requires fuels to contain 29% renewable energy by 2030, Benchev said. Bulgaria meets 7% of this target with biofuels made from farm crops, and the European Commission plans to limit the use of farm crops for such fuels.