London  - The worst fears of a resurgence of terrorist violence in Northern Ireland appeared to be confirmed Tuesday when dissident Republicans claimed responsibility for the murder of a police officer - just 48 hours after two British soldiers were gunned down in the province.

Police Tuesday arrested an 17-year-old male in connection with the shooting of Stephen Carroll, a 48-year-old police officer killed with a shot to the head on a housing estate in the town of Craigavon, near the border with the Irish Republic, late Monday.

Shortly afterwards, the police said a 37-year-old man had also been arrested.

Armed police Tuesday broke into a flat near the scene of the attack as the investigations continued amid rising tension in the town, the BBC reported.

As political leaders vowed to stop the murders from destroying the peace process and the power-sharing institutions led jointly by Protestants and Catholics, a dissident Republican group said it killed Carroll in an ambush Monday evening.

The Continuity IRA, a splinter group of the former Irish Republican Army (IRA), said it carried out the murder.

Carroll, a policeman with 20 years of service, was the first police officer to be murdered by terrorists in Northern Ireland since 1998.

He died after being called to the estate with a colleague by a woman who reported that one of her windows had been smashed in with a brick.

His killing came only 48 hours after two soldiers were gunned down at the gates of Massereene barracks north of Belfast on Saturday in what was the first lethal attack on British troops in the province since 1997.

A separate dissident group, the Real IRA, claimed responsibility for that attack, in which two soldiers and two civilians - one of them Polish - were also seriously injured.

Around 5,000 British soldiers remain in barracks in Northern Ireland following the withdrawal of the bulk of the British army from the province in 2007.

Since then, British soldiers have stopped patrolling the streets of Northern Ireland as responsibility for security in the province passed to the newly-formed Police Service of Northern Ireland (PSNI).

In London, British Prime Minister Gordon Brown condemned the murder of the police officer but vowed that Northern Ireland would not return to the "old days" of sectarian and terrorist violence.

"These are murderers who are trying to distort, disrupt and destroy a political process that is working for the people of Northern Ireland," Brown said.

Brown, who visited the province Monday to pay tribute to the dead soldiers, said the people of Northern Ireland did not "want a return to guns on the street."

Northern Ireland's Protestant First Minister, Peter Robinson called the attack on the police officer "evil" and Sinn Fein, the mainstream pro-Irish republican party, said it was "tragic."

Police chief Hugh Orde appealed to people to show "courage" and come forward with information on the recent killings.

He ruled out calling in the army for support in meeting the new terrorist threat from "disparate small groups of criminals."

Both Robinson and his Sinn Fein deputy, Martin McGuinness, called on the people of Northern Ireland to support the police and report anything they might know about the attackers.

Mistrust and suspicion of the police remains deep-rooted in many Catholic parts of Northern Ireland, where the two communities remain largely divided along religious lines.

During the 30 years, the now disbanded main IRA frequently targeted the Protestant-dominated former police force, the Royal Ulster Constabulary.

But Sinn Fein, under the leadership of Gerry Adams and McGuinness, has given its backing to its successor, the PSNI.

Robinson and McGuinness were on their way to London to fly to the US when the news of the police officer's murder broke.

They returned to Belfast but are still expected to travel to the US for next week's St Patrick's Day celebrations and a meeting with President Barack Obama. (dpa)