Tensions between Irish Rail and trade unions have escalated today after the company wrote to all workers warning them that their demands are "unaffordable".
Both sides are involved in a dispute over payment for post productivity for train drivers. A second morning of industrial action is planned for this Friday.
It is estimated that 40,000 passengers were disrupted by similar industrial action on 23 October.
National Rail and Bus Union General Secretary Dermot O'Leary said: "Writing directly to staff in this fashion, designed as it is, to undermine the trade unions, who are after all directly representing their members is counter-productive and will not get us one jot closer to a resolution of this dispute.
"Our members are furious at this intervention and see it as an insult to a workforce that have fully cooperated in improving the Rail Network in this Country over the last decade.
"The only reasonable way of getting a resolution here is for all stakeholders to fully engage on all of the issues, attempting to disenfranchise workers representatives is bringing a distasteful element to this dispute."
"We wrote to the Minister this morning to express our concern that the line being adopted by his Department was such that it appeared to us to be one-sided and was not a true version of the events that had unfolded at the Workplace Relations Commission over the nine days prior to last Friday weeks dispute.
"We remain wedded to the view that there is a reluctance on the Company side to fully engage on all of the issues at the heart of this dispute, trying to side-line the Trade Unions in writing directly to train drivers is, to us, systematic of what we have been experiencing at the Company over recent times," he added.
