Moscow is seriously troubled by the European Union's investigation into whether Russian gas giant Gazprom has violated EU antitrust laws and hopes that Brussels will not allow it to damage relations with Russia in the energy sector.

"We are closely following the antimonopoly investigation. It is a matter of serious concern for us," Russian Deputy Foreign Minister Alexander Grushko told Interfax.

"We very much hope that in any case, decisions will be adopted that will help maintain the strategic nature of relations between Russia and the EU in the energy sector," he said.