British army experts defused a 600-pound (275-kilogram) van bomb Saturday on the Northern Ireland border, the largest such bomb in more than a year linked to Irish Republican Army die-hards.

British army experts defused the homemade bomb two days after a passing motorist told police about the abandoned van on a border road near the predominantly Catholic town of Newry, a hub for IRA activity. Police and soldiers took more than a day to search the surrounding area, fearful of a potential IRA ambush, before moving in.

Newry's police commander, Chief Superintendent Alasdair Robinson, said the bomb was "a very significant device. If this had exploded, it would have caused devastation."

Robinson said the bomb _ two explosives-filled barrels attached to a detonator and power-timer unit _ was fully assembled, viable and big enough to cause major damage to a town center. He said anybody within 50 yards (meters) of the bomb would probably have been killed had it exploded.

He said the attackers might have abandoned the bomb short of their intended target after encountering a police patrol ahead, as has happened several times previously when IRA dissidents tried to drive car bombs into town centers.

But politicians noted that IRA dissidents made no telephone warnings. The anti-British militants usually issue warnings when leaving bombs in civilian areas, but not when they are trying to draw police into range of a bomb or a second hidden device nearby.

"Clearly this was an attempt to lure a police patrol into that area, with potentially lethal consequences," said Danny Kennedy, a Protestant member of Northern Ireland's power-sharing government who lives near Newry.

Several small IRA splinter groups continue to mount attacks in Northern Ireland in hope of undermining key accomplishments of its peace process, including a stable Catholic-Protestant government and an increasingly integrated police force. The major IRA faction, the Provisional IRA, renounced violence and disarmed in 2005, and its allied Sinn Fein party in 2007 accepted the legal authority of the police.

Since then the IRA dissidents have greatly increased attacks on police officers, usually when they are off duty and more vulnerable. The threat means that officers still cannot live safely in predominantly Irish Catholic districts because the IRA factions have their roots there.

Police say they also must exercise caution when responding to suspected bombs or other reported crimes near Northern Ireland's meandering 300-mile (500-kilometer) border with the Republic of Ireland, where dissidents have greater freedom to operate and attempt roadside ambushes. Saturday's defused bomb was left barely 1,000 yards (meters) from the border.

Last month, two dissidents were convicted of the 2009 murder of a 48-year-old policeman who was shot through the back of the head as he sat in his patrol car. In April 2011, a 25-year-old policeman was killed when a booby-trap bomb detonated under his private car in his driveway.

Both of the dead officers were Catholics, a reflection of how the past decade of peacemaking has dramatically transformed the makeup of Northern Ireland's once-overwhelmingly Protestant police. Today's force is 30 percent Catholic.

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Associated Press writer David Stringer in London contributed to this report.