As a potential buyers were mentioned Croatian national power company HEP and the owner of the other half of Gen-I, the state-owned energy group Gen Energija.

Petrol acquired the stake in Gen-I in 2011 for EUR 25m and the company as a whole has been estimated to be worth EUR 90m today. It last year generated EUR 1.3bn in revenue and EUR 5m in net profit, according to the business daily Finance.

The daily Dnevnik meanwhile writes that Gen Energija has the pre-emptive right to buy Petrol's stake, and that it is offering, according to unofficial information, around EUR 20m for it.

The other potential buyer, according to the paper, is the Croatian group HEP, which jointly operates the Krško Nuclear Power Plant (NEK) with Gen Energija, and which has been aggressively entering the Slovenian market lately.

The Ljubljana City Municipality has picked HEP as its electricity distributor and car parts maker Cimos recently signed a EUR 19m power supply contract with the Croatian energy group.

Petrol has not commented on the reasons for the sale, while both papers note that the company has never had influence on decision-making in Gen-I, while the two actually compete on the electricity and gas market, as Petrol also owns a third of the country's biggest gas supplier Geoplin.