Prime Minister Gordon Brown Monday condemned what he termed the "executions" of two British soldiers in Northern Ireland and said the people of the province were united in their defence of the peace process, dpa reported.
His remarks, during a visit to Northern Ireland, came as the names of the two soldiers killed in Saturday night's attack were released.
They were 23-year-old Mark Quinsey and 21-year-old Cengiz Azimkar, who had both been due for imminent deployment with British forces in Afghanistan.
Two other servicemen and two pizza deliverymen were seriously injured in the attack at the gate of Massereene barracks, north of Belfast.
One of the two injured civilians was a 19-year-old Briton and the other a 32-year-old Polish man who worked for the pizza service, police said.
Brown, who visited the scene of the attack, said the people and the political parties in Northern Ireland were showing "the whole world" that they backed the peace process.
The attack took place because of the success, and not the failure, of the peace process started 12 years ago, Brown said.
The Real IRA, a Republican splinter group which has claimed responsibility for the murders, had "no place in the politics of Northern Ireland," said Brown.
"These are callous people who carried out executions outside these barracks," he added.
Brown later had talks with top representatives from all political parties in the province, including Sinn Fein, the mainstream pro-Irish Republican party led by Gerry Adams.
Earlier Monday, Adams condemned the killings as "an attack on the peace process" and said his party would cooperate with police in catching the killers.
The attack was "wrong and counterproductive," he said, without explicitly condemning the murder of British soldiers.
Although Sinn Fein, the mainstream pro-Irish Catholic party, remained opposed to the presence of British troops in Northern Ireland, that could "not justify what occurred," said Adams.
Commentators said it was remarkable that Adams, who led Sinn Fein from its former close association with the paramilitary Irish Republican Army (IRA) to a party in government in Northern Ireland, publicly backed police efforts to track down the killers.
"It is the logic of our position and we do have a responsibility to be consistent," said Adams. "The logic of all of that is that we support the police in the apprehension of those involved."
Sinn Fein has a traditionally difficult relationship with the police and security forces in Northern Ireland.
Over the three decades of conflict, the IRA often targeted Northern Ireland's former police force, the Royal Ulster Constabulary, but Sinn Fein has accepted the legitimacy of its successor, the Police Service of Northern Ireland.