"I'm confident that as a big fighter against corruption, Gregor Virant will know what to do if the anti-corruption commission finds something wrong," she told reporters after a visit to the Hrastnik coal mine.

She said what was needed first was to determine the facts, noting that she did not know all the details. The Commission for the Prevention of Corruption "has already said something about this" and media reports suggest it was additionally interested in "certain things".

Her statement comes after the anti-graft watchdog last week cleared Virant of accusations that he used his influence to buy cheap tickets from a special Adria allotment for employees and ticket agents.

But the daily Dnevnik revealed Monday that Virant had indeed personally ordered tickets from Adria's sales director, which the paper said he had not divulged to the anti-corruption commission.

The revelation sparked calls from the ranks of the opposition that Virant resign, a chorus that even Ljubljana Mayor Zoran Janković joined today.

Janković, who resigned as president of the Positive Slovenija (PS) after the anti-graft watchdog found he misreported millions worth of assets, said Bratušek should sack Virant.

If the media reports are correct, Virant personally arranged the tickets, which means he committed perjury. The commission should file criminal charges against him, he said.