There are 30 coal regions in Europe that are aware that their long-term future cannot be linked to coal mining, and the people there need to be trained and retrained, Timmermans said.

"I can commit to you here that we will look at this plan, given that Bulgaria has serious challenges in its energy sector. We will ensure that the transition in the coal-producing regions takes place in a fair way, and I promise you - I am committed that no one will be abandoned and forgotten," Timmermans said.