Naftogaz Ukrainy has filed a lawsuit against the European Commission in the European Court of Justice seeking to cancel the decision enabling Russian Gazprom to significantly increase the gas volumes it ships on the OPAL gas pipeline and the Nord Stream pipeline.

"Approval of this decision without consultations with Ukraine violates Article 274 of the association agreement between Ukraine and the EU, as well as the EU's obligations under the Energy Charter agreement and under the agreement on formation of the Energy Community," Naftogaz said in a press release.

Naftogaz maintains that in making the decision, the European Commission exceeded its authority and that the decision violates EU directive 2009/73, does not promote competition, poses threats to the security of supplies to Ukraine and other Eastern European countries and also hinders the effective functioning of the EU and Energy Community's domestic market, since it reinforces the dominating position of Gazprom and associated companies.