Labor MPs could refuse to co-operate with an Ombudsman's probe into rort claims, after the Andrews government moved to use parliamentary rules to avoid scrutiny.

Premier Daniel Andrews has come under fire for repeated efforts, including spending taxpayers' money in the courts, to stop Ombudsman Deborah Glass from investigating allegations that Labor MPs' electorate officers were illegally used for political campaigning at the 2014 election.

Premier Daniel Andrews has been criticised over Labor's efforts to halt the Ombudsman's probe. Credit:Penny Stephens

On Wednesday morning, leader of government business Jacinta Allan moved a motion to assert the right of privilege, meaning the investigation ordered by the upper house (the Legislative Council) "cannot be taken to apply to current or former members of the Legislative Assembly".

The move follows a failed government appeal in the Supreme Court to stop the Ombudsman from investigating the claims.