Gardai were last night questioning a man from Northern Ireland in connection with an ammunition find in Co Louth.
Armed police surrounded and stopped a vehicle at Heynestown, near Dundalk, as the man drove north along the M1 around 4.30pm yesterday.
Gardai recovered a small quantity of bullets, as well as a balaclava from the SUV.
The vehicle was seized and is now being examined.
A 33-year-old man, believed to be from Newry, was arrested and is being detained at Drogheda Garda Station under Section 30 of Offences Against The State Act.
Gardai refused to comment on reports that the arrest is part of an ongoing operation against dissident republicans.
A spokesman said: “One man in his 30s has been arrested following an operation in Dundalk, Co Louth, involving the Garda Emergency Response Unit.
“Gardai seized a 4 X 4 vehicle in the course of this operation and are examining its contents.”