The Energy Community (EnC) Secretariat sent an Opening Letter to Serbia addressing the failure to carry out an environmental impact assessment (EIA) for the extension of the Drmno coalmine in the Kostolac basin in 2013. The Drmno coalmine has been in operation since 1987 and provides for the fuel supply of the nearby coal-fired thermal power plants. In 2013, the operator sent a request for another expansion of the mine, which was approved by the competent authority without requesting an EIA. In the Opening Letter, the Secretariat comes to the preliminary conclusion that the decision not to carry out an EIA was taken by the competent authority without regard to a significant expansion of the surface of the mine.