Austrian opposition parties agreed Wednesday to set up a parliamentary commission of inquiry into alleged corruption by officials from the ruling People's Party (OVP) after its leader Sebastian Kurz stepped down as chancellor on the weekend.

Kurz denies wrongdoing but has been placed under investigation along with nine others including senior aides on suspicion of corruption offenses to do with using public funds to manipulate public opinion in favor of Kurz when he was seeking to take over as party leader and later chancellor.

He stepped down on Saturday at the behest of his junior coalition partner, the Greens, to save their coalition. He has been succeeded as chancellor by close ally Alexander Schallenberg, a diplomat and relative newcomer to politics who says he will work closely with Kurz, who remains party leader.

"We believe that what we have seen until now is just the tip of the iceberg," lawmaker Kai Jan Krainer of the Social Democrats told a joint news conference with colleagues from the two other opposition parties in parliament.

Parliamentary commissions of inquiry in Austria have the power to seize documents and question witnesses under oath.

An earlier commission on possible corruption under Kurz's previous coalition with the far-right obtained troves of text-message exchanges that became part of prosecutors' corruption case against Kurz and others.

Kurz is separately under investigation on suspicion of perjury over testimony he gave to that commission. Kurz, who is now also taking over as his party's top lawmaker in parliament, says all allegations against him are false.

While the opposition parties can set up such a commission without the two ruling parties' support, Krainer said Kurz's conservatives can delay its approval and it might not be able to hold its first session until next year.