A number of items have been seized by detectives investigating violent dissident republican activity in the North West.
A number of searches were conducted at various locations in Derry/Londonderry this afternoon (Monday 25 May).
Items were seized, including electronics.
Four men, aged 29, 31, 35 and 36, who were arrested in the city last night (Sunday 24 May) under the Terrorism Act, as part of the investigation, have been released following questioning.
The investigation is ongoing.