Former Victorian premier Daniel Andrews has defended the actions of senior members of his government, whom the state’s anti-corruption watchdog found engaged in “serious and concerning” conduct in their dealings with the leader of the firefighters’ union.

A long-awaited report by the Independent Broad-based Anti-corruption Commission, tabled in parliament on Wednesday, stopped stopped short of making any findings of corrupt conduct.

But it found senior members of the Andrews government engaged in “serious and concerning” conduct in their dealings with Peter Marshall – the secretary of the United Firefighters Union (UFU) – when negotiating pay deals for the Country Fire Authority (CFA) and Metropolitan Fire Brigade (MFB), and their later amalgamation into Fire Services Victoria (FSV).

This included “actions contrary to policy, procedure and codes of conduct, deliberate attempts to conceal and mislead, and the misuse of information”.

The findings led the Victorian opposition to claim the state is being led by a “gangster government”.

The Operation Richmond report said the investigation began in 2018 following a tip-off that Marshall “blackmailed or otherwise compromised” Andrews “to change his position on the CFA EBA”.

But Ibac found no evidence of blackmail and did not substantiate the allegation, which both Andrews and Marshall denied.

In a rare public statement on Wednesday afternoon, Andrews said the report found “no evidence whatsoever to to support the false and completely outrageous claims that I had been blackmailed to force a favourable outcome” for the UFU and its members.

“These claims were baseless when they were made almost a decade ago, and they remain baseless today,” he said.

Andrews said he acted in the public interest to resolve the “spiteful and dysfunctional enterprise bargaining dispute” that had “dragged on for years” between the CFA and the UFU.

“Fire chiefs were spending more time in the Fair Work Commission than running their organisations. That was not acceptable to me or to the government when community safety was on the line,” he said.

Andrews also defended the amalgamation of the fire services, saying it was done in the “best interest of community safety”.

The report largely centres upon the Andrews government’s first term, following its election win in 2014. During the election, the UFU campaigned heavily against the then-Coalition government over pay and conditions.

In February 2015, Labor began negotiations for a new enterprise bargaining agreement (EBA) for the CFA, which the then Brunswick MP, Jane Garrett, oversaw as emergency services minister.

But the Ibac report said by the end of 2015, negotiations had “reached an impasse” and the UFU had begun industrial action. Efforts to resolve the industrial dispute through Fair Work Commission conciliation and external mediation failed and in early 2016, negotiations broke down completely.

Andrews told Ibac the relationship between Garrett and the union had become so ‘“dysfunctional” and that he considered “she could play … no useful role in resolving this matter”, so he asked his special minister of state, Gavin Jennings, to take over. The head of the Department of Premier and Cabinet, Chris Eccles, asked his deputy, Tony Bates, to assist Jennings.

“At some point I’ve said to [Jennings], ‘You need to go and fix this. This needs to get fixed’,” Andrews told Ibac during an examination.

Ibac’s report said Jennings, Bates and Marshall, accompanied by a small team of UFU negotiators, held negotiations over four days in April, “with the first sessions held at a rented meeting space, and the final session on 12 April held in a hotel meeting room”. An unnamed federal Labor senator also attended as an intermediary.

On 12 April, Ibac said Jennings sent a text to Andrews that read: “Handshake has occurred – it’s done!”, to which he responded, “Very good”.

Ibac said photographs were also taken of the unnamed senator “with full champagne glasses in hand and sparkling wine bottles on the table, toasting towards the camera” with three UFU negotiators.

A day later, Marshall met Andrews at 1 Treasury Place with a new “UFU proposal”. Bates told Ibac he had led the development of the draft agreement, which led the anti-corruption watchdog to form the view the meeting was “not genuine but staged”.

Ibac found Garrett and some cabinet members, who signed off on the EBA proceeding through to the next step of the bargaining process, were not told of Jennings’s negotiations.

In a lawfully intercepted phone call in March 2019, Marshall gave an account of the origin of the EBA to a ministerial adviser: “This agreement was negotiated with fuckin’ Jennings in a back room. It was endorsed by fuckin’ Andrews and cabinet.”

Garrett resigned from the ministry as she did not want to back an EBA she was opposed to. She died from cancer in 2022.

The CFA board, which Ibac said was also unaware of the deal, was dismissed after they failed to endorse the EBA. Ibac said new board was appointed through an “opaque and non-competitive process.”

Ibac found the undisclosed deal allowed Marshall to “exert extraordinary influence over the negotiations” and later on the MFB EBA, which ended up with many of the same terms.

Ibac’s report also raised concerns about the way the 2019 bill that amalgamated the MFP and paid parts of the CFA into the FRV passed parliament. It found Marshall had sought to secure the support of a crossbench MP by hiring their relative days before it was due for a vote in the upper house.

In another intercepted phone call in June 2019, Marshall told a friend the MP was “100 per cent behind us … just to make sure we just employed [their relative].”

Marshall, meanwhile, was also granted “privileged access” to MPs, Ibac found, and “sensitive or confidential information” was provided to him once by an MFB board member and twice by Bates,who has since been appointed the secretary of the Department of Education.

In a statement on Wednesday, Marshall said Operation Richmond was Ibac’s second report into “myself and the UFU that has concluded no corrupt conduct”.

“I feel vindicated by both outcomes, but very disappointed by the damage to my reputation caused by this failed investigation and the constant leaks arising from it.”

Victoria has a higher threshold for what constitutes corrupt conduct than in NSW, with Ibac requiring that the conduct would constitute a relevant criminal offence.

Ibac “did not establish that the conduct investigated met all required elements to make findings of corrupt conduct”, the report said.

The opposition leader, Jess Wilson, called on the premier, Ben Carroll, to sack Bates.

“This report today demonstrates that this is a gangster government. Corruption is in Labor’s DNA, and Victorians have had enough,” she said.

Carroll told reporters on Tuesday morning Bates had taken a leave of absence. He said the report was “10 years in the making” and he was “not in the cabinet when all of these matters began”.

While he said he was yet to read the report, the behaviour described was both “poor” and “intolerable”.

“I will take action. I will accept the recommendations and get on with implementing them,” Carroll said.

The release of the report comes after years of legal attempts by the UFU to keep it secret, including a high court challenge.