The national executive of the National Bus and Rail Union (NBRU) will meet later today to decide whether to restart industrial action in opposition to plans by the Minister for Transport to break up CIÉ.
All CIÉ unions are due to meet with Department of Transport officials next week on January 15th for renewed talks on the future of the company.
However, unions representing rail and bus workers have been angered over interviews given by Mr Brennan in which he restated his plans to introduce competition from private operators on certain routes.
It now appears likely that the CIÉ unions will opt to withdraw from the talks when they meet this Thursday, making industrial action affecting on rail and bus services increasingly likely.
This weekend the NBRU said it intends to restart industrial action within a fortnight.