Richard Di Natale has called for the expulsion of Greens members responsible for leaks against the party’s candidate, Alex Bhathal, before the loss in the Batman byelection.

The Greens leader has flagged a review and purge of party members responsible for damaging leaks accusing Bhathal of bullying after his claim on Sunday that traditional Greens voters had been turned off by the alleged sabotage.

In Saturday’s byelection Labor’s Ged Kearney won with 54.63% of the two-party-preferred vote, a 3.6% swing away from the Greens who were favourites to win after successive gains at recent federal elections, a strong campaign against the Adani coalmine and the Liberals’ decision not to run a candidate.

In a statement on Monday the Victorian Greens co-convenors, Rose Read and Colin Jacobs, said the campaign was “marred by the actions of a person or persons who ... [leaked] confidential information regarding an internal dispute in order to damage the campaign”.

“It is an attack on the very mission of the Greens. It can have no place in our party,” they said.

The co-convenors said they would “initiate an investigation into this aspect of our campaign”. “This investigation is about what happened in Batman, but we do expect that learnings from it can be applied to future campaigns.”

Asked on Sunday if he would seek the expulsion of those responsible for leaks, Di Natale told ABC’s National Wrap they were a “major factor” in the loss.

Batman byelection: Labor's Ged Kearney defeats Greens' Alex Bhathal Read more

“And yes – I think anybody who has been deliberately leaking to the media in an effort to undermine – not just the candidate but obviously the federal team [should be expelled].”

Di Natale said there was no place in the party for people who could not accept democratic outcomes and chose to undermine them by “leaking and sabotage”.

The Greens leader said the animosity towards Bhathal was “purely personality-based” because of a “personal grievance” against her, rather than philosophical differences.

On Monday the former Greens Western Australia convenor, Graham Bowland, called on Di Natale to resign, describing it as “manifestly unhelpful” for the federal leader to apply public pressure and prejudice the outcome of internal investigations.

“This is not the first time Richard has called for those who dissent from his personal vision of the party’s future to be forcibly removed from our organisation,” he said. “We would have to be fools to think that Richard’s call for a purge is limited to those allegedly responsible for the alleged leaks in Batman.”

The Labor senator Kimberley Kitching seized on Di Natale’s comments, suggesting they amounted to a threat to expel whistleblowers and were an attempt to “to solve a bullying saga with more bullying”.

Kimberley Kitching 🇦🇺 (@kimbakit) Greens party solution to toxic faction-ridden culture in Batman: hunt down & expel “scores” of whistleblowers who made bullying complaints against their former candidate #auspol #batmanvotes



Every party has internal drama but you can’t solve a bullying saga with more bullying. https://t.co/z01ftrSZo9

The Victorian Greens are not the only branch engaged in factional infighting. In New South Wales the upper house member Jeremy Buckingham has been fighting off a complaint that was supported by the federal senator Lee Rhiannon, and Di Natale’s former chief of staff Cate Faehrmann has taken legal action against the party after she was prevented from contesting an upcoming preselection.

On Monday Di Natale told ABC’s AM that only a “small number” of people were responsible for leaks in Batman. He said he retained the confidence of his colleagues as leader and talked up the party’s successes at the Northcote state byelection, its doubling of representation in the Western Australian parliament and the election of an MP in the Queensland lower house.

The Greens leader said that there were “peaks and troughs” in the minor party vote, but the long-term trend for major parties was down.

Kearney’s campaign in Batman was reportedly boosted by an intervention from the Catholic school sector, which deployed 30,000 robocalls in the electorate in favour of Labor, which has promised to restore the sector’s funding.

On Monday the finance minister, Mathias Cormann, said the Batman result was not an endorsement of Labor’s plan to end cash refunds for excess imputation credits.

He told Radio National “the Greens have been at each other’s throat for most of the campaign” and that had put off voters.

“It’s a safe Labor seat ... and the Greens were particularly unattractive at this election given the level of infighting on the ground in the lead up to the election.”