The Ljubljana court confirmed for the STA that two of Janković's former associates, Mitja Marinšek and Stanislav Brodnjak, are under investigation along with the founder of Ljubljana-based real estate company BSD, Boris Milevoj, while Janković's lawyer Aleksander Čeferin confirmed for the daily Delo that police are also investigating Janković.

The charges for abuse of office against Janković were filed in January 2007 and were based on a 2006 audit by Deloitte & Touche into the operations of Mercator in the 2001-2005 period, when Janković was at the helm.

According to media reports, irregularities were found in Mercator's deals with the companies owned by Janković's two sons and in the purchase of the site for a Mercator store in Serbia's Niš.

The prosecution requested court investigation against all four suspects in May 2011 and the investigating judge ordered the launch of court proceedings on 17 February, but all four appealed to the decision.

The Ljubljana District Court senate then deliberated on the matter on 16 April and rejected all four appeals as ungrounded. This made the decision on launching investigative procedure final, the court explained.

It could not yet confirm though that Janković was also under investigation, because he has not received the court's notice yet although it was sent to him twice. But his lawyer Čeferin confirmed form Delo that the investigation had been launched and stressed that Janković was innocent.

He said the proceedings were "a form of political pressure" on Janković, who is also the president of the biggest opposition party, Positive Slovenia (PS).

"If you look at who is involved in these proceedings, then it is all clear," Čeferin said in a reference to unofficial information obtained by Delo that the investigation was requested by Jaka Brezigar, the son of former State Prosecutor General Barbara Brezigar.

Janković, Marinšek and Brodnjak face a prison sentence of one to eight years. Milevoj, a representative of Cyprus-based company Facim, faces charges of complicity to abuse of office.