The expert who reviewed mental health at Victoria's fire service says it is "bizarre" that the firefighters' union is blocking the release of his report.
Peter Cotton started an independent review of mental health in the MFB after three firefighters committed suicide.
But the United Firefighters Union has taken the MFB to the Fair Work Commission to block the report's release, arguing it vilifies firefighters.
"This response is absolutely unprecedented and frankly quite bizarre, in my experience," Dr Cotton told 3AW on Tuesday.
"The union's response is now actually putting members' mental health and wellbeing at risk, I'll go that far to say that."
A union spokeswoman said the union was not making a public response to the report, but it would be represented at Wednesday morning's Fair Work hearing.
Dr Cotton said he had a "good discussion" with the union during consultation for the report, and it was entirely independent and fair.
"If management had attempted to interfere or influence or massage the report, I would have pulled the plug," he said.
He also said the union stopped a letter from Beyond Blue chairman Jeff Kennett, written to support firefighters and their families, from being sent out.
The case will be heard at the Fair Work Commission in Melbourne on Wednesday at 11am.
Readers seeking support and information about suicide prevention can contact Lifeline on 13 11 14 or the Suicide Call Back Service on 1300 659 467.
