Forensic examinations were carried out today on a 275kg (600lb) explosive device that was defused in south Armagh yesterday.
The bomb was found along the Forkhill to Silverbridge road. A command wire led from the scene to a firing point over the Border in Co Louth.
Garda and PSNI officers are examining the theory that dissident republicans, most likely from the Real IRA, were behind the failed attack.
The viable device, which was bigger than the 1998 Omagh bomb, was made safe by British army technical officers yesterday.
A Belfast newspaper received a warning on September 1st that an explosive device had been left somewhere in south Armagh. This was passed on to the PSNI which began aerial surveillance of the region.
Police said yesterday that due to the vague nature of the warning it took until last Saturday to locate the device and evacuate the immediate vicinity on Carrive Road.
The Irish Timeswas told that the exact position of the bomb followed the passing of more information to the police by a member of the public.
One local source also suggested that an ambush of a police patrol may have been abandoned and that the bombers may have been reluctant to return to the bomb for safety reasons, or because the scene may have been monitored.
Sinn Féin President Gerry Adams earlier said it had been made clear that those days were gone.
"It's quite clear that the local people do not support what is happening. Some people were very, very frightened and outraged and I endorse what [Sinn Féin Minister for Regional Development in the Northern Executive] Conor Murphy has said: Let those who support these groups, or group, explain their rationale and let them come and talk to whoever they want and we include ourselves in this," he said.
"We want to see all of these actions ended and we want to see the peace process built upon as opposed to being pulled back, the way these people are trying to pull it back."
It is the third major bombing attempt so far this year which has been foiled by the police.
In January, a 145kg device was abandoned near a school just outside Castlewellan, Co Down. The size of the device and the apparent improvement in the dissidents’ bomb-making capacity alarmed the police. In May another significant device was made safe in a field in Co Fermanagh.
The latest attempted bombing follows a spate of dissident republican attacks including the murders of two British soldiers and a PSNI officer in March.
Minister for Justice Dermot Ahern said those who planted the bomb were trying to drive a wedge between North and South and he condemned their actions as anti-republican.
“We spent years negotiating with the British to demilitarise the Border. That hard work led to the complete removal of oppressive watchtowers and massive cuts in troop numbers,” said Mr Ahern. “Those involved in this action are trying to reverse that work – to stop normalisation – to remilitarise the Border, cutting North from South once more. Their actions are anti-republican,” he said.