Mr Wrack bad-mouthed Scottish secretary John Duffy and tried to stop another colleague, Roddy Robertson, from speaking to the press.
The damaging row can be traced to last year's decision by the firefighters' union to strike in opposition to the UK Government's pension cuts. Union members in Scotland, where the issue is devolved, accepted a revised offer from the SNP Government and agreed to shelve strike action. It is understood Scotland's no-strike position angered Mr Wrack, who wanted a UK-wide stance.
Mr Robertson said: "I have been chastised on more than one occasion by my general secretary about telling the members what the up-to-date position was with our negotiation in Scotland."