Police forensic experts on both sides of the border are trying to establish if there are any links between the bomb components seized outside Dundalk at the weekend and unexploded devices recovered in Northern Ireland.
A detailed examination of the bomb-making plant at the rear of a house in the Mount Pleasant area and the two modified cylinders discovered bolted to a trailer was continuing yesterday.
Anti-terrorist officers are trying to uncover connections between the incidents as they build up a dossier on suspected members of the Real IRA faction that has remained loyal to the imprisoned founder of the group, Michael McKevitt.
The faction has regrouped around a couple of key members and is based mainly in the Louth-south Armagh area.
McKevitt is serving a 20-year sentence in Portlaoise jail for directing the activities of a terrorist organisation.
Saturday's raid, which followed a week-long surveillance and intelligence-gathering operation, confirmed that the Mount Pleasant plant was being used to manufacture the shell of the bomb.
It was intended that the two cylinders would then be packed with explosives when they had been brought across the border and readied for detonation.
Meanwhile, two men, aged 23 and 52, who were detained at the bomb plant by armed gardai were still being questioned at Drogheda station last night.
They can be held without charge until this evening.