Detectives from PSNI Terrorism Investigation Unit investigating violent dissident republican activity have today made a fourth arrest.
Earlier a PSNI spokesman said properties in Drumquin, Benburb and Armagh were searched and a number of items have been seized.
He said the arrested individuals - two women, aged 31 and 23, and a 30 year old man - are being questioned at the Serious Crime Suite at Musgrave police station in Belfast.
Later, detectives from PSNI Terrorism Investigation Unit made a further arrest following searches in counties Tyrone and Armagh.
The 55-year-old man is being questioned at Musgrave police station in Belfast.