The crackdown was mounted ahead of next week’s visit to the Republic by Prince Charles.
A controlled explosion was carried out in Co Louth in the early hours of this morning as part of an investigation into dissident activity.
An Army Bomb Disposal Team arrived on the scene in Dromiskin at 10.20pm last night.
The Defence Forces said component parts were made safe at the scene and the explosive material was destroyed by controlled explosion.
The scene was declared safe at 3am.
Two other bomb disposal teams were also deployed yesterday.
A team made safe two viable improvised explosive devices in the Manorhamilton area of Co Leitrim.
A suspect device was found during a vehicle search by gardaí and a cordon was put in place for public safety.
In Co Wexford, a bomb disposal team made safe component parts of explosive device making equipment in Courtown.
The component parts were found during a garda search of a private residence in Courtown yesterday evening.
A small number of nearby houses were evacuated for a time.
The six men – who have links to dissident republican terror groups – are being held under the Offences Against the State Act.
They are being questioned about the seizure of pipe bombs, bomb components, a firearm and ammunition in three counties.
Gardaí carried out their searches yesterday in Leitrim, Louth and Wexford.
The operation comes ahead of the visit to Ireland next week of the Prince of Wales and his wife, which has led to increased security measures and monitoring of dissident republicans.