Forty five Essex fire brigade staff face disciplinary action after allegations they wrote to MPs and councillors about budget cuts.
Some of the letters were passed to the chief fire officer who said claims being made by employees were untrue.
But the Fire Brigades Union said the letters were prompted by concerns over working practices and cuts.
And it criticised MPs and councillors for breaching confidentiality by passing on the letters.
Members of the Fire Brigades Union (FBU) have been asked to highlight worries about budget cuts and changes to working practices by writing to their local MP or councillor.
However, brigade chiefs reacted angrily after they were given copies of the letters.
Deputy chief fire officer for Essex Gordon Hunter said management actions had been blamed for the deaths of children and this was blatantly untrue.
He added: "In this case, serious allegations and nasty comments were made about groups of employees.
"Firefighters employed by Essex are expected to act professionally at all times and we will fight to maintain the respect of the public.
"The crux of this issue is a two-year dispute with the FBU over cuts and changes to work practices and it grieves me that loyal members of the union are being used as pawns.
"Only 2% of out 2,000 staff are involved and that's about 45 people. We get on with the rest."
The FBU wants disciplinary action halted and has complained about MPs' actions to the Parliamentary Standards Committee.
Adrian Clarke, from the FBU, said Essex Fire Service management was sensitive to criticism at the time they were trying to introduce cuts.
"This heavy handed use of discipline is indicative of their style of management."
But he said the breaches of confidentiality were a more serious matter and the FBU had written to the MPs and councillors concerned asking for an explanation of their action.
They have also contacted the Parliamentary Standards Committee and the Speaker of the House of Commons to clarify if these actions were allowed.
Baroness Angela Smith, a former minister for the fire service, said: "Confidentiality in this case is not like a priest but MPs and councillors get thousands of letters raising issues of all kind.
"This is the first I've heard of this kind of action. You never pass on the name and address of the person raising the issue although you may contact those concerned.
"People might become reluctant to contact MPs or councillors if they feel their confidentiality has been breached."