A van bomb found north of the Irish border contained a wheelie bin packed with 500lbs of homemade explosives and may have been destined for a town centre, police in Northern Ireland say.
The device, which sparked a major security alert close to the Irish border, was defused on Friday night.
The foiled attack, which politicians say could have caused a massacre on the scale of the 1998 Omagh attack, has been blamed on dissident republicans opposed to the peace process.
A number of controlled explosions were carried out on the vehicle found at a section of the main road between Belfast and Dublin, near Newry.
Police Board member Jonathan Bell said the bombers had planted “500lbs of hatred aimed at murder”. He compared it to the 800lb car bomb that killed 29 people, including a woman pregnant with twins, in Co Tyrone town in 1998.
“Had this device exploded the consequences are almost too horrible to contemplate,” he said.
A DUP representative added: “500lbs of explosives were planted to kill and we could have had another example of mass murder on our hand today.
“Just as last week we had many children and familites running past the explosive device that robbed our society of the life of a talented young officer, so today we could have had serious fatalities.”
The incident comes as detectives hold three men over the murder of Constable Ronan Kerr.
A 33-year-old man was detained in the Omagh area yesterday over the booby trap bomb attack that killed the 25-year-old Catholic officer outside his home in the Co Tyrone town on Saturday.
Police yesterday were also given five more days to question a 26-year-old man arrested in Scotland on Wednesday and re-arrested on Thursday, plus a 40-year-old man arrested near Omagh on Thursday.
The under-car bomb that killed Pc Kerr was also blamed on dissident republicans who remain violently opposed to the peace process.
It has also emerged that the groups are continuing to target policemen in the wake of Pc Kerr’s murder.
Senior police sources have said the public outcry following the young officer’s death has had no influence on the mindset of extremists, who remain focused on killing members of the security forces.
Detectives have evidence the dissidents have been actively targeting Police Service of Northern Ireland (PSNI) personnel since the weekend murder.
Officers do not want the nature of the intelligence to be made public for investigative reasons, but they say murder plots are being uncovered at a rate of one a fortnight.
One PSNI source added: “There is absolutely no indication the community outrage has had any impact on the mindset of the dissidents.”
Meanwhile, a Democratic Unionist Party representative said: “Will Northern Ireland stop going forward because of the bullying of a minority of terrorists? No.”
In a reference to the widespread condemnation of the murder of Pc Kerr, he added: “The message was crystal clear from last week when our society came together as one to reject death.”