The Slovenian government had said it expected binding bids for the 75.5 percent controlling stake in its largest airport this month. "Vinci confirms that it is a candidate in the tender to buy Ljubljana airport," a Vinci spokesman said.

Slovenian daily newspaper Finance, citing unofficial sources, said Vinci is offering about 50 euros per share, which would value the company at 96.7 million euros.

It said German airport operator Fraport was among bidders for Aerodrom with a similar offer. Fraport gave no immediate comment to Reuters.

According to Finance, Italian airport operator Gruppo Save and international investment firm Friedmann Pacific were also bidding for Aerodrom. The two companies gave no immediate comment to Reuters.

Finance said Slovenian state investment firm SDH, which is managing the sale of Aerodrom, is expected to continue negotiations with the two or three highest bidders by Friday.

Shares in Aerodrom were up by 4.76 percent to 48.2 euros by 0814 GMT, pushed up by the sale expectations, while the blue-chip SBI index was down 0.18 percent.

Miro Cerar, who is well placed to become the next Slovenian prime minister according to opinion polls, told Reuters on Wednesday that he was against the sale of Aerodrom but was not sure if the sales process could be stopped.

Slovenia will hold an election on July 13 triggered after centre-left Prime Minister Alenka Bratusek resigned in May after she lost the battle for the leadership of the Positive Slovenia party. The outgoing government last year earmarked 15 firms for privatisation, among them Aerodrom, in order to boost its income and improve corporate governance. Two of those firms have been sold.