The detention is part of Operat Arbacia.
Police investigating the activities of the New IRA have arrested a 65 year old man in Dungannon, County Tyrone.
It's after a search and arrest operation yesterday.
The PSNI says the arrest, as part of Operation Arbacia, an ongoing investigation into the New IRA, is specifically looking at the organisation's finances.
The man has been released and a report is being prepared for the Public Prosecution Service.