The theft of cabling from the rail line near Tipperary Town in the early hours of last Sunday morning disrupted train services for several hours that day.
Gardai in Tipperary Town are investigating the theft of cabling from the rail line at the townland of Newtown near Tipperary, which damaged the central signalling system between Limerick Junction and Thurles.
Iarnrod Eireann spokesperson Jane Cregan said the signalling system was down for a number of hours on Sunday morning and was repaired just after 2.30pm.
During the time the system was down, she explained that Iarnrod Eireann staff had to manually signal the trains and this resulted in Cork, Kerry and Limerick train services to and from Dublin running one hour late.
A spokesman for Tipperary Town Garda Station said they believed the cabling was stolen for its copper content, which is very valuable at the moment.
He said two men from the Tipperary Town area found in possession of cabling were arrested on Sunday and questioned at Tipperary Town Garda Station in relation to the rail line theft.
A file on the case is now being prepared for the Director of Public Prosecutions.