Transport workers begin voting today on whether to take industrial action over plans to deregulate the industry.
Members of SIPTU and the National Bus and Rail Union (NBRU) are angry at what they see as the Minister for Transport, Mr Brennan's failure to consult them about plans to break up CIÉ.
The workers were further annoyed by an interview with Mr Brennan in The Irish Timestwo weeks ago in which he said a "summer of discontent" could ensue as a result of his plans to press ahead with franchising out 25 per cent of Dublin Bus routes.
In a statement issued today, SIPTU said the interview amounted to the Minister "unilaterally terminating the discussions between his officials and the CIÉ unions on the future of Dublin Bus".
The industrial action envisaged could include an all-out strike. SIPTU national secretary Mr Noel Dowling said: "Without pre-empting the outcome of the ballot, it is envisaged that a programme of industrial action would involve an escalating series of stoppages on separate days in the three operating companies".
The NBRU general secretary, Mr Liam Tobin, said the union was also seeking a mandate for all-out strike from its 4,000 members.
He said the Minister had assured unions in October of last year that there were no plans to privatise Dublin Bus but the following month announced the opposite. Mr Tobin said: "He wasn't saying it might happen, he was saying it would happen, that no one would stop him".
Mr Tobin also claimed talks between unions and the Department of Transport were discontinued by the Department without the unions being notified.
The results of the ballot will be known by the end of the month.