Police believe dissident republicans carried out an attempted bombing in Armagh on Saturday night, when a 500 lb car-bomb was left outside the city's police station.
However, they said it was too early to say which particular grouping was responsible. The bomb, which was made safe by army technical officers, was still being examined yesterday.
The car-bomb was left opposite the city's police station on the Newry Road and was spotted by police at 11.15 p.m.
A number of homes in the area were already being evacuated when a telephone warning was received at 11.30 p.m. A controlled explosion was carried out shortly before midnight.
The car, a white Toyota Carina, was stolen in Dublin last month and had been fitted with false number plates. The bomb contained 500 lb of home-made explosives.
The attempted bombing was condemned as "stupid and reckless" by the North's political development minister, Mr Paul Murphy. He said it came at a time when the North stood on the brink of a lasting settlement.
The SDLP mayor of Armagh, Mr Pat Brannigan, said it was an attack on the people of the city as well as on the police station.
Mr Peter Osborne, of the Alliance Party, said it was "a cynical effort to derail the Yes vote at the most critical time."