A car bomb made of 90kg of homemade explosives hit a police station in Derry, Northern Ireland in 2010 [File: EPA]

A 25-year-old Catholic policeman who had just joined Northern Ireland's police force was killed when a booby-trap bomb exploded as he got into his car in the town of Omagh.

No group claimed responsibility for Saturday's attack, but police and politicians universally blamed Irish Republican Army (IRA) dissidents who have repeatedly planted bombs underneath the private cars of off-duty police officers.

Until Saturday, such booby-trap attacks had badly maimed two other officers but killed nobody. It was the first lethal attack on Northern Ireland security forces in more than two years.

In previous statements, the dissidents have stressed their determination to target any Irish Catholic who joins the Northern Ireland police force.

Building Catholic support for the previously Protestant-dominated police force is a central goal of Northern Ireland's peace process. 

But reflecting the exceptional political solidarity in Northern Ireland today, leaders from both the British Protestant and Irish Catholic sides of the community condemned the bombers and vowed to bring them to justice.

In Dublin, newly-elected Irish prime minister Enda Kenny called the killing "a heinous and pointless act of terror."

"Those who carried it out want to drag us back to the misery and pain of the past. They are acting in defiance of the Irish people. They must know that they can never succeed in defeating the democratic will of the people,'' said Kenny.

Neighbours of the victim in the Gortin Road district of Omagh - a town synonymous with the greatest horror of the entire Northern Ireland conflict - said he had just entered his car when it exploded. The car was turned into a blazing wreck.

A violent history

Dissidents opposed to Northern Ireland peacemaking shot dead two off-duty British soldiers and a policeman in March 2009. Last year, they detonated half a dozen car bombs outside security installations, businesses and a courthouse but caused little damage and wounded nobody seriously.

In the 1980s, IRA weapons engineers designed under-car booby trap bombs specifically to kill the driver, and in Saturday's attack, the bomb appeared to explode immediately after the target got into the car.

Since 2007, IRA dissidents have planted dozens of such booby-trap bombs under the private cars of police officers. Most bombs failed to detonate, and several dud devices fell off onto roadways. Two policemen did lose their legs in such attacks in May 2008 and January 2010.

IRA dissidents committed the deadliest single bombing of the entire Northern Ireland conflict in Omagh on Aug. 15, 1998, when a car bomb detonated amid a crowd of evacuated shoppers and workers. Twenty-nine people, mostly women and children, were killed. 

No dissident was ever successfully prosecuted for that attack, so the 1998 attackers remain at large.

Northern Ireland's police force has been radically transformed over the past decade in a major success for the peace process. A policy of favoring Catholic recruits helped to turn the force from 8 per cent Catholic in 2001 to
30 per cent Catholic today.

But Catholic recruits remain particularly vulnerable to attacks by IRA dissidents, who chiefly live in working-class Catholic areas. Catholic police officers are unable to live or safely visit relatives in those areas.

The IRA killed nearly 1,800 people in a failed 1970-1997 campaign to force Northern Ireland out of the United Kingdom. Most IRA members renounced violence and disarmed in 2005.

Those peace moves cleared the way in 2007 for Protestants and Catholics - led by the IRA-linked Sinn Fein party - to create a new unity government for Northern Ireland.