A car bomb exploded last night outside the courthouse in Newry, Northern Ireland, police said. There were no initial reports of any injuries in the blast.

Police said the vehicle was abandoned at the front of the building in the Co Down town at around 10pm. Officers were in the process of evacuating the area when the car exploded.

Northern Ireland Secretary Shaun Woodward said: "This is an act of senseless violence by a small handful of people who refuse to accept the people's overwhelming support for the peace process. The best message that could be sent to them is a powerful rejection of violence through the completion of devolution."

Suspicion is bound to fall on republican dissidents opposed to the peace process. The incident comes only days after a mortar bomb failed to detonate outside a police station in the nearby Co Armagh village of Keady.

The chairman of the nationalist SDLP in Newry, Gary McKeown, condemned those responsible. "Lives could have been lost as a result of this bombing," he said. "It serves absolutely no purpose and does nothing for the community, or the cause of a united Ireland. If people want to advance their beliefs, they should enter the democratic process and debate with their political opponents, rather than resorting to violence. Planting bombs outside courthouses will achieve nothing."

Earlier this month, police on both sides of the Irish border launched separate operations against dissident republicans. Police in Northern Ireland arrested two men and a woman in connection with the murder of Constable Stephen Carroll, the first PSNI officer killed by terrorists in the province.

The Continuity IRA shot the 48-year-old policeman dead on a housing estate in Craigavon, County Armagh, on 9 March last year. His murder came just 48 hours after the Real IRA killed two British soldiers outside the Massereene barracks in Antrim. In September police discovered a massive 600lb bomb in the south Armagh village of Forkhill.

On Sunday, Republican Sinn Féin, political allies of the Continuity IRA, claimed masked undercover soldiers carried out surveillance on two housing estates in Lurgan, Co Armagh, in recent weeks. They claimed the men were scouting the areas in white civilian vans. Republican Sinn Féin said the soldiers belonged to the Special Reconnaissance Regiment.

The alleged presence of SRR soldiers – formerly known as the 14th Intelligence Unit – is controversial because British troops are meant to have been pulled off the streets, especially in nationalist areas.