Sava is Gorenjska's biggest shareholder with a 37.7 percent stake but was ordered to sell its stake in 2015 by the Bank of Slovenia, which believed Sava, which has a heavy debt burden, was not financially strong enough to support Gorenjska.

Sava, which has been trying to sell the stake since last year, said in a statement that it had decided to sell its stake, subject to its shareholders' approval, but did not name the buyer. STA's report did not say what price had been agreed for the sale.

According to local media reports, Sava was fined 500,000 euros ($588,000) by the central bank in October for failing to sell its Gorenjska stake by a set deadline.

Gorenjska has about a 4.7 percent share of Slovenia's banking market.

AIK currently owns 21 percent of Gorenjska but has been aiming to gain a majority stake and earlier this year gained central bank permission to increase its stake to above 50 percent.