INLA firing party at the wake of convicted child killer Martin McIlkerney in May this year
A 57-year-old-man arrested as part of the same investigation remains in custody.
The men were arrested under the Terrorism Act in the Galliagh area Derry and Strabane.
Mobile phones, documentation and other electronic devices were also seized by police during three searches.
Part of the operation was linked to an investigation into shots being fired following the death of former INLA prisoner Michael McElkerney in May this year.
Detective Inspector Tom McClure said the INLA is a “priority” due to “the level of threat, risk and harm they pose to our communities” and the “breadth and depth of their criminality”.
He said police believed the INLA was behind a recent spate of shootings in Derry
