THE chief executive of Irish Rail is holidaying in Mauritius as last-ditch efforts are made to prevent a strike by train drivers.
Tens of thousands of commuters face travel chaos on Sunday and Monday as a result of a pay dispute.
However, David Franks - who earns a salary of €211,000 - is on holidays on the Indian Ocean island.
More than 2,100 rail workers are to stage the first national strike in over 13 years.
Union leaders and opposition TDs described his decision to take annual leave this week as "extraordinary".
The absence of the rail chief at home could scupper any chance of striking an 11th-hour compromise, they warned.
The Herald has learned Mr Franks will not return from Mauritius until Monday.
Transport Minister Paschal Donohoe's spokesman said the minister had "no comment".
Mr Donohoe, who is currently spending a few days in Kerry, has previously described the decision by workers to strike as a "slap in the face" of taxpayers.
Fianna Fail said Mr Donohoe's silence raised questions over whether he is "content" with Mr Franks' absence.
"The minister needs to clarify whether or not he is content with the CEO of Iarnrod Eireann remaining on holidays during such a crucial phase of this dispute," said the party's transport spokesperson Timmy Dooley.
Barry Kenny, of Irish Rail, said the chief executive "may be away", but he is in contact on an ongoing basis and is "leading and managing the situation".
People in leadership positions, while they may take breaks, they are never off-duty, he added.
Up to 15,000 GAA fans planning to attend the All-Ireland senior football semi-final between Mayo and Kerry face disruption.
More stoppages are planned for September 7, the day of the All-Ireland hurling final and on Monday, September 8. There will also be a stoppage on September 21 when the GAA football decider takes place.
The National Bus and Rail Union (NBRU) said Mr Franks' decision to go abroad has angered workers.
"It is extraordinary to think that the chief executive of a semi-state company involved in a major industrial dispute would be out in the Indian Ocean during a week like this," NBRU general secretary Dermot O'Leary said.