Theresa Villiers: David Black killers will not succeed
Secretary of State Theresa Villiers has said the killers of prison officer David Black would not destabilise Northern Ireland's political situation.
Mr Black, 52, was attacked on the M1 motorway in County Armagh as he drove to work on Thursday.
A car drove up beside his vehicle and fired a number of shots. His car veered into a ditch and he died at the scene.
Ms Villiers said the murderers had acted in defiance of the will of the people of Ireland.
She added the murder had been "utterly futile".
"Those who seek to pursue their objectives by violence will not succeed," Ms Villiers said.
"The future of Northern Ireland will only ever be determined by democracy and by consent.
"That is a clear message coming from Northern Ireland in the wake of this tragedy, from political leaders, from church leaders and from across the wider community."
She said the government would continue to "bear down hard on terrorism".
"We will continue to devote the appropriate resources to enable the Police Service of Northern Ireland and its partners to continue their excellent work in protecting people in Northern Ireland," Ms Villiers said.'Sickening crime'
Shadow secretary of state Vernon Coaker said the murder was a "sickening and deplorable crime".
"This was not a political act, it was not done on anyone's behalf or to achieve any aim, it will not further any cause. It was the cold-blooded evil murder of an ordinary man," he said.
Mr Coaker also paid tribute to Northern Ireland's prison officers: "They do a remarkable job in very difficult circumstances.
"An attack on any one of them is an attack on the criminal justice system, the law and indeed the community."
The MP for North Belfast, Democratic Unionist Nigel Dodds, said the murder was "a despicable and callous act of terrorism".
"It's all the more appalling because of its total and utter futility and pointlessness in the wider context of Northern Ireland," he said.
"Across Northern Ireland there is a united coming together in a common stand against these men of evil."
Mr Black, a father-of-two from Cookstown in County Tyrone, was the first prison officer to be murdered in Northern Ireland in almost 20 years.
The Police Service of Northern Ireland (PSNI) have said they believe dissident republican paramilitaries were responsible for the attack.
The murder has been condemned by all political parties in Northern Ireland.