In a press release on Monday, the Commission said its investigation focused on the markets for downstream wholesale supply of gas and retail supply of gas in Slovenia.

Geoplin's activities concern the supply, trade and related services in the natural gas market. Petrol is active in retail and wholesale of petroleum products, sales of commercial goods and natural gas. It provides both electricity and natural gas to final consumers.

The commission found that on the gas wholesale market, the parties' customers already source, or are planning to source, gas directly from the Central European Gas Hub located in Austria.

In addition, there are no constraints on interconnection capacity between Slovenia and neighbouring member states.

It also found that on the gas retail market, customers have a number of alternative suppliers available and the transaction will have a limited impact on the retail gas supply market structure in Slovenia.

Petrol will get a majority stake in Geoplin under a swap contract signed with the Slovenian Sovereign Holding in June 2016.

In exchange, the state is to get a majority stake in Plinovodi, a company managing Slovenian gas pipelines, while it will also keep a 25% stake in Geoplin.