Rail travel in the North has been severely disrupted after three bomb alerts on tracks running from Belfast to Derry and Dublin.
A series of telephone warnings, beginning at 11.30 p.m. on Sunday, warned of devices on the tracks between Moira, Co Down, and Lurgan, Co Armagh, Belfast and Lisburn Co Antrim, and between Antrim town and Derry city.
Passengers on the Belfast to Dublin service, as well as those travelling from Antrim to Derry and on the busy commuter route into Belfast from Lisburn, all had to be bussed to their destinations as security forces examined the tracks.
A suspect device was later found on the track at Finaghy, between Belfast and Lisburn. Police and railway officials warned that disruption would continue at least until this morning, as searches for other devices and possible booby traps continued.
There have been 32 alerts on the cross-Border rail route this year. While many alerts have been declared hoaxes, a number have been genuine and, in some cases, booby-trap devices were left as bombers targeted those searching for bombs.
Politicians and the RUC blamed dissident republicans for the attacks and threats.
A spokeswoman for public transport company Translink condemned those behind the disruption and apologised for the inconvenience to passengers.
"It's very frustrating for everyone," she said. "This is the first day back to school after the Easter holidays, so a lot of children have been affected as well as people trying to get to work."
SDLP Assembly member Mr John Dallat accused the dissidents of embarking on "an exercise in partition".