His arrest was in relation to last week's Police Service of Northern Ireland (PSNI) data breach which saw the names of 10,000 officers and staff published online in response to a freedom of information request.

Details released included the surname and first initial of every employee, their rank or grade, where they are based and the unit they work in.

Police had earlier said they detained a 50-year-old under the Terrorism Act following a search in the Dungiven area on Friday.

Earlier this week, a 39-year-old man was detained following a search in Lurgan, Co Armagh, as part of the same investigation.

He was questioned on suspicion of collection of information likely to be of use to terrorists, and later released on bail.

On Monday, PSNI Chief Constable Simon Byrne said he believed the information was in the hands of dissident republicans.

It followed the posting of documents from the leak on a wall near a Sinn Fein office in Belfast.

The PSNI has said in the past week it suffered two other data breaches relating to officers' personal details.

Missing sections of a PSNI notebook that fell from a moving car on the M2 in Belfast contained details of 42 officers and staff. The sections have not been recovered.

In a separate incident, a document containing the names of officers and staff was stolen along with a police-issue laptop from an officer's car on 6 July.