Two men were being questioned today about a series of bomb attacks on the homes of Sinn Féin members in Northern Ireland.
The arrests were made at locations close to Ballymena, Co Antrim, where the loyalist paramilitary campaign has been centred.
Security sources said pipe bomb devices left at one property and another elaborate hoax at a separate house in the staunchly Protestant town were being linked to the Ulster Volunteer Force.
It is understood one of the men was arrested in the village of Ahoghill, a village just outside Ballymena.
A PSNI spokesman confirmed the men, who were taken to Gough barracks in Armagh for questioning, had been arrested under the Terrorism Act. They were being interviewed about serious crime in the Ballymena area, he added.
SDLP MLA, Mr Sean Farren, said there were indications that the "Ulster Volunteer Force has breached its ceasefire and gone back to war."
"A slide back into organised violence cannot and must not be tolerated. The situation is very simple: all paramilitaries must cease all their criminal and violent activities."
"Today and tomorrow the people of Ireland are going out to vote on their future. There can be no place in that future for guns and pipe bombs."