A 38-year-old Belfast man is one of three people in custody being questioned about ongoing dissident republican activity.
The suspect was detained on Tuesday by detectives from the PSNI’s Serious Crime Branch.
A 32-year-old woman and a 39-year-old man are also still being questioned in connection with dissident republican activity in Derry.
The pair were detained on Monday after detectives found ammunition and explosives during a raid in the Beechwood area.
All three suspects are being held at the serious crime suite in Antrim.