Two suspect explosive devices have been found in the North in the past 24 hours.
SDLP MLA Dolores Kelly
PSNI bomb squad officers are investigating a suspected pipe-bomb that was discovered by workmen on the railway line between Lisburn and Portadown just before 2pm yesterday.
Speaking to ireland.com, SDLP MLA Dolores Kelly said that she believed the device to be the work of dissident republicans.
"Local youths have been involved in these activities for a while now, and they are clearly being trained by someone," she said.
Continuity IRA slogans began appearing in the area in July, she added.
There are reports that youths have this afternoon set alight a barricade they have erected over the railway line near Lurgan's Kilwilkie estate.
The British army last night defused a bomb left on the doorstep of a house in Carrickfergus.
The pipe-bomb was discovered outside the house in the Windslow area of the town just before 1am. A number of items were removed from the scene for investigation.
A PSNI spokeswoman said that the house was vacant at the time, and that detectives are working to establish a motive for the attack.