Two Co Louth brothers are due to appear in court today charged with possessing the 940lb bomb intercepted by gardai as it was about to be driven into Northern Ireland.
Gardai believe the bomb was being prepared by a dissident republican group, based in the Dundalk area, and was to have been detonated in a Northern town to coincide with the completion of the vote-counting of Friday's referendum on the North.
It is the third time that the Garda Special Branch has intercepted and stopped bomb attacks by this dissident group at critical points in the peace process this year. The same group tried to carry out bombings on St Patrick's Day, when the Sinn Fein leader, Mr Gerry Adams, was meeting President Clinton in Washington, and again on Good Friday, when the political negotiations reached their climax.
Just before 5 p.m. on Saturday armed gardai stopped two cars, a Toyota Carina and BMW, and arrested two brothers within 300 yards of the Border on a quiet country road at Carrickaneena.
The driver of the BMW attempted to break out of the Garda trap and was rammed and stopped by one of the Garda cars. Both men were then arrested and taken to Dundalk Garda Station.
The Army's Explosive Ordnance Disposal (EOD) team from Monaghan was called and examined both cars. The EOD officers carried out a test explosion on some of the mixture contained in bags in the cars.
Last night, a senior Garda source said it was believed the bomb had been assembled by people who support the group known as the 32-County Sovereignty Committee, and who style themselves the "real IRA".
The officer confirmed that a large number of gardai from the armed Emergency Response Unit (ERU) had been brought up to Louth, in the weeks leading up to the election and for the days immediately after it, to keep an eye on suspected dissidents.
"We are not a bit surprised. We had a contingency plan in place and had anticipated this. Extra patrols had also been in place since Thursday evening and indeed we had thought something might have been planned for the day of the actual vote," he added.
The Garda's National Surveillance Unit had been monitoring the activities of figures associated with the dissident group recently.
A preliminary examination of the vehicles revealed bags of what appeared to be homemade explosives. The examination revealed 440lbs was being carried in the Toyota Carina. It was travelling behind the BMW, which had been stolen from a house in Malahide, Dublin, on Friday and was fitted with false number plates.
There were 500lbs in the BMW, along with a booster tube packed with explosive material and a quantity of cortex detonating wire. There was no detonator. Gardai say the bomb was not primed. It is believed the bombers' plan was to switch all the explosives to the boot of the BMW, which was fitted with lorry shock absorbers to disguise the weight being carried in the boot.
The men arrested are in their 30s and are natives of Dundalk. One is a former soldier, who served as a driver in the Army from 1980 to 1983.
They are well known to gardai for alleged involvement in subversive activities. They are suspected of being supporters of the "real IRA", which is allegedly under the control of another Co Louth man, who is a former quartermaster general of the Provisional IRA.
The DPP is expected to decide later today whether the men will be brought before the Special Criminal Court and charged with possession of explosives.