Federal MP Anthony Byrne will be the first witness to front an anti-corruption inquiry into allegations of branch stacking within the Victorian Labor Party.

Operation Watts, a joint probe by the Independent Broad-based Anti-corruption Commission and the Victorian Ombudsman, will on Monday begin public hearings into allegations of branch stacking by Labor MPs and their staff.

Premier Daniel Andrews ordered the IBAC investigation in June 2020, after an expose by The Age and 60 Minutes caught party powerbroker Adem Somyurek handing over cash and using parliamentary staff to create fake branch members.

Mr Somyurek quit the party before he was expelled but retained his upper house seat, while factional allies Robin Scott and Marlene Kairouz resigned from cabinet.

All three MPs deny the branch-stacking claims.

Mr Byrne, who represents the Holt electorate in the outer south-eastern suburbs of Melbourne, was embroiled in the scandal after it was revealed some of the footage in The Age and 60 Minutes expose was recorded in his office.

Explosive texts written by Mr Byrne were released by Mr Somyurek after his former factional ally agreed to co-operate with IBAC investigators.

Operation Watts public hearings are expected to last five weeks and will also examine allegations that public money intended to fund community associations was misused for party‐political work or other improper purposes.

Electorate officer and former ministerial office executive assistant Ellen Schreiber and ministerial adviser and former electorate officer Adam Sullivan, are also appearing before the inquiry on Tuesday and Wednesday respectively.

Branch stacking involves recruiting or signing up members for a local branch of a political party to influence the outcome of candidate preselections for parliament.

It is against Labor rules to pay for other people’s membership. Party members must sign a form declaring they have paid for their own memberships.

The scandal prompted reform of the Victorian branch of the Labor Party, including the expulsion of about 1800 members found to be “non-genuine” and the suspension of voting rights of all other members until 2023.

-AAP