A 500-pound (225-kilogram) van bomb defused Saturday near the Irish border probably was destined to strike a town center or landmark building in a bid to undermine Northern Ireland's election campaign, police and political leaders said.
Police Chief Superintendent Alasdair Robinson said the dissident IRA bomb left Thursday night under a freeway overpass was properly constructed but abandoned before it could be detonated. He said it was likely that the attackers stopped short of their intended target because of a police road checkpoint.
Robinson said the bomb _ roughly double the size of a half-dozen car bombs that Irish Republican Army dissidents detonated last year in Northern Ireland _ "was a sophisticated device and it would have been devastating had it reached its destination."
Last year's bombs outside security installations, courthouses and a hotel all caused little damage and no serious injuries. The last lethal car bomb in Northern Ireland also was the most deadly: an August 1998 attack by the Real IRA splinter group on the town of Omagh that killed 29 people, mostly women and children.
A Protestant member of a cross-community panel that oversees the police, Jonathan Bell, said Saturday's defused bomb was similar in size to the Omagh bomb. "We could have had another example of mass murder on our hands today," he said.
The bomb alert closed the major road and rail line connecting Belfast and Dublin for all of Friday. It showcased the public's low regard for the threat posed by dissident IRA bombers, whose devices usually fail to explode properly.
After police shut down the main road south of the border town of Newry, impatient motorists unwilling to take a diversion moved or drove over traffic cones and "road closed" signs. BBC Northern Ireland footage showed hundreds of cars driving directly past the van Friday morning before police reinforced the barriers.
Robinson said IRA dissidents made two brief telephone warnings Thursday night to a suicide prevention line and Newry's hospital. But he said they were so vague that police didn't know what to look for, and located the van thanks only to a tipoff from a passing motorist.
The van, he said, was stolen near Dublin in January and fitted with fake Republic of Ireland license plates, underscoring the fact that dissident groups operate more freely south of the border.
Detectives are continuing to question three suspected IRA dissidents over last weekend's killing of Ronan Kerr, a 25-year-old Catholic police recruit, who died when a booby-trap bomb detonated under his car in his driveway. He was the first member of Northern Ireland's security forces to be killed by IRA dissidents since March 2009.
Police say several splinter groups opposed to the IRA's 2005 decisions to disarm and renounce violence are trying to increase their violence in the run-up to a May 5 election of the Northern Ireland Assembly. The electoral campaign follows a surprisingly successful, stable four-year run for the British territory's Catholic-Protestant administration, whose members all face re-election.
The splinter groups remain committed to the traditional IRA goal of overthrowing Northern Ireland's government and forcing the territory into the Republic of Ireland. Most IRA members support the 2007 decision of the Sinn Fein party, which represents most the province's Irish Catholic minority, to form a compromise government alongside the British Protestant majority.
Sinn Fein leader Gerry Adams appealed on his blog Saturday for the dissidents to give up.
"The people of this island demand that you stop," wrote Adams, a former Belfast IRA commander. "Your achievement has been to unite us all in opposition to your actions. It is time to end these futile attacks on the peace process, they will not succeed."
He told supporters of the dissidents: "Don't be fooled into thinking that you are helping the IRA. The war is over. The IRA is gone. The IRA embraced, facilitated and supported the peace process. When a democratic and peaceful alternative to armed struggle was created the IRA left the stage."
Associated Press reporter Jill Lawless in London contributed to this report.