Police in Strabane, Co.Tyrone investigating dissident republican activity have arrested a second man.
The two men, aged 45 and 55, are being held by anti-terror detectives in Belfast.
It follows searches of a property and land in the Back Row and Riverside areas.
Anti-Terror Detectives from the PSNI have arrested a man in Strabane, County Tyrone.
The 43-year-old is being held in an investigation into suspected dissident republican activity.
Officers have searched a property as well as areas of land in the Back Row area and the Riverside.