Belfast-Dublin train: Refurbished Enterprise has licence suspended after doors open
The newly-refurbished Enterprise trains have had their safety licence suspended in the Republic of Ireland after passenger doors opened mid-journey.
There were two incidents - one in December and one last week - on the service run jointly by Translink and Irish Rail.
Translink said at no stage were any passengers in danger.
All the refurbished trains are due to be operating on the Belfast to Dublin route from the end of February.
However, the Railway Safety Commission (RSC) has issued a prohibition notice on NI Railways, banning them from operating in the Republic of Ireland.
The RSC said the notice was independent of its approval of the newly re-furbished Enterprise Trains and that the doors or door circuits were not part of the re-furbishment project.
One of the refurbished trains was unveiled by Translink in November and had been undergoing a three-month trial.
It was one of four de Dietrich trains upgraded by Translink and was described by the company as a "major milestone" in its £12.2m NI railways upgrade programme.
New livery and interiors were also included as well as a significant overhaul of the train's mechanical systems and a new electronic passenger reservation system.
In response to the latest incidents, Translink said "internal investigations have highlighted that the two door incidents are unrelated in nature and at no stage were passengers in any immediate danger".
"A technical investigation and remedial action is currently under way across the Enterprise fleet involving specialist door contractors and the train door manufacturer.
"The Enterprise train remains out of service while this is ongoing."
Translink has postponed the introduction of a new timetable for the Enterprise train service to Dublin.
An earlier 06.15 GMT Belfast departure time had been due to begin at the end of January.
But the journey time would have taken longer - almost two and a half hours.
However Translink has now said that "alternative options" are being looked at. Passengers have been consulted by Translink and Iarnród Éireann about the proposed changes.
The service is operated jointly by Translink and Iarnród Éireann.
"The companies will work together to review feedback from the timetable consultation processes," a statement from Translink read.
It added they hoped to finalise a new timetable by the end of "the first quarter of 2016".