Four men are being questioned in Clare in connection with suspected subversive activity.
The men, from Armagh, Monaghan and two from Limerick, were arrested at a Garda checkpoint on the outskirts of Kilrush last night on suspicion of being members of an unlawful organisation.
They are aged between 36 and 57 and are being held at Kilrush garda station under Section 30 of the Offences Against the State Act.
The men can be held without charge for an initial period of 24 hours.
Gardaí are continuing to conduct a follow up search near the scene of their arrest today.