The 47-year-old, who was detained in Londonderry on Saturday, has been released pending a report to the Public Prosecution Service (PPS).
The three men who remain in custody are aged 36, 39 and 40.
The 36-year-old was arrested in Newry, County Down, on Sunday morning and a property was searched.
He was taken to Musgrave police station in Belfast for questioning.
Meanwhile, a 35-year-old man arrested in west Belfast on Saturday was later released unconditionally.
Police investigating dissident republican terrorism have released a 47-year-old man but are continuing to question three other men.