Melbourne firefighters will rally in coming weeks and consider industrial action over changes to a controversial deal on their pay and conditions.
The United Firefighters Union said it had been instructed by members to seek legal advice on whether they can take industrial action, after an "explanatory memorandum" was added to a deal struck by the Metropolitan Fire Brigade board.
The note would give the MFB's leadership unrestricted control over entitlements and staff rostering, the union said.
The union's Victorian secretary Peter Marshall said firefighters were angry.
"Anger, betrayal, and extreme disappointment," he told AAP after a meeting of members on Friday.
Firefighters will be surveyed in the coming week about whether they want to move a no-confidence motion against the MFB board, Mr Marshall said.
An agreement on wages and conditions had been struck by the board and the state government in January.
Emergency Services Minister James Merlino on Thursday said there "are some matters being resolved in the Fair Work Commission" before the deal was put to firefighters.
Shadow attorney-general John Pesutto on Friday said the latest comments from Mr Marshall were proof the union had done a "backroom deal" with now-Premier Daniel Andrews before the 2014 election.
"Victorians now have every right to ask - what was in that deal?" he told reporters.
Mr Marshall dismissed Mr Pesutto's claim as "laughable".
"He probably got it from the same fairytale that his mother used to read him as a child," he said.