The probe will assess whether supply agreements between Qatar Petroleum companies exporting LNG and European importers have hindered the free flow of gas within the European Economic Area (EEA), in breach of EU antitrust rules.
Commissioner Margrethe Vestager, in charge of competition policy, said in a written statement that energy had to flow freely within Europe, "regardless of where it comes from".
"We have opened an investigation to look at whether there are problematic territorial restriction clauses in gas supply contracts with Qatar Petroleum," she said.
Vestager underlined that such clauses might harm competition and prevent consumers from enjoying the benefits of an integrated European energy market.
Qatar Petroleum is the largest supplier of LNG globally and to Europe, accounting for around 40 percent of the EU's overall LNG imports, according to the EC.
The company controls several firms that produce and export LNG to Europe.
The Commission will further investigate whether Qatar Petroleum's long-term agreements (typically 20 or 25 years) for the supply of LNG into the EEA contain direct and/or indirect territorial restrictions.
(Anadolu Agency, 21/06/2018)