The NBRU has said rail unions are considering the "nuclear option" of striking over Christmas and New Years, writes Cillian Sherlock.
The comments follow news that Independent Alliance Ministers, including Transport Minister Shane Ross, plan to go on a peace keeping mission to North Korea.
Reacting to the news, the National Bus and Rail Union has said it is "appalled" that the Transport Minister would consider going to North Korea, saying he "refuses to work towards sorting a major rail dispute".
General Secretary Dermot O'Leary said he thought he had "fallen into a deep sleep" and woken on April Fools Day.
"The suggestion, in the middle of a major rail dispute, that Shane Ross, Minister for Transport, would go off to North Korea in a bizarre attempt to establish relations with a regime that has an appalling record on human rights, where the word democracy is banned, is nothing short of dumbfounding," he said.
MinisterJohn Halligan has written to the North Korean Embassy in London seeking to visit the state to meet with Kim Jong-un in January or February, in a bid to calm nuclear tensions.
Minister Halligan said Finian McGrath would also be on the trip.
"[It] is a clear demonstration of how much Mr Ross and his Independent Alliance colleagues are out of touch with what is happening on their own doorstep," he added.
Mr O'Leary said Ireland would be better served if "those with notions of grandeur [and] desires to become International Statesmen" carried out the duties they were elected to do.
"That the Minister would seek to pander to a missile toting megalomaniac, while rail unions are coming under pressure to take the nuclear option of striking over the Christmas/New year period is simply preposterous," he said.
The offices of Shane Ross have been contacted for comment.