Victoria's former emergency services minister Jane Garrett is filing a formal complaint over "distressing conduct" by United Firefighters Union boss Peter Marshall.
Ms Garrett revealed she was finalising a complaint against Mr Marshall in a statement on Tuesday.
The same statement claimed an adviser to Premier Daniel Andrews intervened between Ms Garrett and Mr Marshall last year because of the UFU secretary's behaviour.
Mr Marshall has repeatedly denied Ms Garrett's accusations of bullying - including reports he threatened to put an axe in her head.
At a Tuesday caucus meeting Ms Garrett and her staff were accused of making damaging leaks to the media, some even calling for her to resign, it has been reported.
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A staffer for Ms Garrett was accused of leaking a 2015 memo from the premier's adviser John Paul Blandthorn which suggested Mr Andrews consider asking Mr Marshall to be more respectful to ministers, MPs, staff and departments.
Ms Garrett's statement on Tuesday denied her staff had contacted journalists about the matter.
She also said Mr Blandthorn had "always looked out for me, including brokering an arrangement that Mr Marshall would not contact me" in September 2015 after his "distressing conduct towards me" during disciplinary proceedings over a fire commander's behaviour.
Ms Garrett says she will now make a formal complaint about Mr Marshall's behaviour.
"Given the Premier's recent comments that people should avail themselves of 'avenues of complaint' if they feel they have suffered mistreatment (after questions relating to allegations that Mr Marshall threatened to put an axe in my head) I have been finalising a formal complaint about the treatment that I and my staff have received during my tenure as Minister," she wrote.
The complaint will be "progressed through the appropriate independent channels".
Ms Garrett resigned from her ministerial position in June after refusing to agree to a pay deal for the CFA, believing it would hand too much power to the UFU.
Mr Andrews then pushed the contentious deal through cabinet and installed a new CFA board to back it.
But the Volunteer Fire Brigades Victoria took the matter to court, successfully delaying CFA workers from voting on the agreement until a Supreme Court trial in September.
Ms Garrett says she was subpoenaed on Tuesday to appear at the trial.
A spokeswoman for Mr Andrews said the premier "has consistently said that anyone who behaves inappropriately deserves condemnation".
"Any complaint made by Ms Garrett should be properly dealt with."
AAP has contacted Mr Marshall for comment.
Outside parliament on Tuesday, after appearing before a committee investigating the state's fire preparedness, Mr Marshall said he was "not going to entertain that rubbish" over claims of bullying.
