Letter bomb addressed to Northern Ireland Secretary Theresa Villiers is intercepted

Staff were evacuated and a stretch of Belfast's Limavady Road was sealed off as the area was made safe

Northern Ireland Secretary Theresa Villiers (Getty Images)

A letter bomb addressed to Northern Ireland Secretary Theresa Villiers was discovered on Tuesday at the offices of the First Minister in Belfast. Bomb disposal experts arrived at Stormont Castle after the letter was found in the post room.

Staff were evacuated and a stretch of the city’s Limavady Road was sealed off as the area was made safe.

The discovery was the latest in a sustained campaign. Letter and parcel bombs have been a tactic of republican and loyalist terror groups since the 1970s, but have seen a resurgence in recent months.

Two letter bombs were recently sent to the police, one in Londonderry and the other to the Chief Constable of Northern Ireland. Another was posted to the Public Prosecution Service in Londonderry. Dissident republicans were blamed in each of these cases.

Ms Villiers, who was in London on Tuesday meeting the former US diplomat Richard Haass, said she “utterly condemned” the attacks.

“If those responsible think that this kind of criminal activity will further any agenda, then they are completely mistaken.”

The Home Office has heightened the threat from extremists opposed to the peace process to “severe” in recent months. They have been responsible for the deaths of two soldiers, two police officers and a prison guard in recent years.

Northern Ireland’s First Minister, Peter Robinson, condemned the action. “Those responsible for sending this, and other devices, through the post have absolutely no regard for the lives of postal workers and staff working in offices,” he said. “They will not further any aim or objective by their vile and callous deeds. Northern Ireland will not be dragged back by terrorists who have nothing but misery to offer.”