A 40-year-old man has been arrested under the Terrorism Act in Derry as part of an investigation into the INLA.
Detectives from the PSNI's Paramilitary Crime Task Force made the arrest on Monday night after searching two properties in the city with the help of the force's Tactical Support Group.
A mobile phone was also seized during the operation.
The man was last night still being questioned.
A PSNI spokesperson said: "The search, and subsequent arrest, is part of an investigation into the activities of the INLA in the north west".
He added: "We’re grateful for the support of our partner organisations and of local communities; and I’m keen to reiterate our appeal for anyone with information, or indeed concerns, to contact detectives on 101".
