The NBI did not reveal any details. However, the daily Večer on Saturday quoted sources as saying that the investigators were looking into the relations between the core company and its subsidiaries, as well as ACH's operations in Slovenia and abroad.

Moreover, the director of Grand Hotel Union, a company in ACH group, said investigators came to talk to him. However, alleged syphoning was not the only topic they discussed, according to Bogdan Lipovšek, who would not reveal any details to the paper.

He told Večer in an interview published a week ago that he opposed further syphoning of funds from the hotel.

Lipovšek has previously revealed to the media that he was informed by the vice-president of Hilton hotel chain that an alleged representative of the ACH was offering four of the group's Ljubljana-based hotels for only EUR 50m.

Moreover, in late December, the ACH confirmed a record dividend payout that benefited managers who carried out one of the first and biggest management buyouts in Slovenia in 2008.

ACH has meanwhile launched bankruptcy protection on Thursday, buying five months of time to reach an agreement with 16 creditor banks on long term-reprogramming of debt, which reportedly amounts to EUR 129m.