More than £80,000 was lost on cross-border train fares because of bomb alerts, it has been revealed.
A total of 11,000 passengers were missed because of a string of attacks centred mainly on the line near Lurgan, Co Armagh, and blamed on dissident republicans.
The main trouble spot has been a three-mile stretch around Lurgan. There have been 18 line closures between Belfast and Portadown since April.
Hoax bomb alerts and stone-throwing youths have regularly put the six miles of track between Lurgan and Portadown out of action, impacting on the express service between Belfast and Dublin.
The information was revealed following an Assembly question from DUP MLA George Robinson.
He said: "The Enterprise service is a vital element of our transport infrastructure. This is why it has been repeatedly targeted by dissident republican criminals.
"I am concerned that some £80,000 plus of costs has been accumulated by the service as a consequence of lost passengers due to terrorist activity.
"These criminals have nothing to offer the community and are seeking to strangle an important infrastructure component of our local economy."