Presenting the petition to reporters in Ljubljana on Thursday, the head of of the deputy group of the coalition Democratic Party (SDS), Jože Tanko, said that the law was also not specific enough on the substance and definition of phenomena.

Apart from the deputy groups of the SDS and its coalition partner New Slovenia (NSi), the petitioners include MP Franc Pukšič of the People's Party (SLS), Bojan Starman of the Citizens' List (DL), MP for the Italian minority Roberto Battelli and all three unaffiliated MPs.

They propose to the Constitutional Court to handle their petition as a priority, while they also suggest suspending implementation of the act pending the court's ruling on the matter.

Tanko said that a report by the Commission for the Prevention of Corruption ought not to cast a shadow of a doubt about the correctness and fairness of oversight of any official, but that it appeared that procedures in the case of some officials had not been run correctly.

"Findings by such a body need to be clear, unambiguous and should not be insinuations," Tanko said, arguing that the anti-graft watchdog was always hiding behind the phrase "risk of corruption".

"If someone is investigating someone else's assets, they probably must ascertain beyond doubt whether this is corruption or not."

"Such phrasing by the Corruption Prevention Commission is very like those we have been witnessing in the trial of Janez Janša in the Patria case," Tanko said, adding that the findings were based on a surmise "which is then built into a story, and legal proceedings are launched that will not end".

The SDS announced it would challenge the anti-graft law soon after the Commission for the Prevention of Corruption issued a report on the assets of party leaders which singled out Janša and Positive Slovenia (PS) leader Zoran Janković as failing to properly account for their assets.

This triggered a government crisis as coalition partners have began quitting the coalition after Janša failed to heed their call to resign.

A petition for constitutional examination of the law had already been filed last year by the Administrative Court, which is currently deliberating on Janša's and Janković's complaint against the graft report.