The Police Service of Northern Ireland has arrested and is questioning a 39-year-old man in Co Armagh in relation to last week's "extremely serious" data breach.

“Detectives investigating criminality linked to last week’s freedom of information data breach have carried out a search in Lurgan today, Wednesday 16 August, and made an arrest,” the PSNI said in a statement.

“A 39-year-old man has been arrested on suspicion of Collection of Information likely to be useful to Terrorists and is being questioned by Detectives at Musgrave Serious Crime Suite.”

Detective Chief Superintendent Andy Hill said: “We are working tirelessly to address the risk posed to officers and staff.  

“Today’s search operation, and subsequent arrest, is just one piece of a largescale operation.

“We will continue in our efforts to disrupt criminal activity associated with this freedom of information data breach and to keep communities, and our officers and staff who serve them, safe.”

The Police Service of Northern Ireland (PSNI) is investigating after information about its current employees was posted online on Tuesday, August 8.

Assistant Chief Constable Chris Todd, Senior Information Risk Owner, said that following a routine Freedom of Information (FoI) request, data contained within a spreadsheet was published on a legitimate FoI website on August 8.

This included the surname, initials, rank/grade, role, and location of all serving officers and staff.  

This data was available to view on the website for a period of up to three hours before it was removed.

The same day it announced the August 8 data breach, the PSNI also confirmed that another data breach took place on July 6 when a spreadsheet containing the names of roughly 200 officers and staff was stolen from a private vehicle in Newtownabbey near Belfast. A police issue laptop and radio are also thought to have been stolen during the theft. 

The PSNI has apologized to staff and officers for the breach and has attributed the initial breach to human error.

On Monday, PSNI Chief Constable Simon Byrne said that the police force was "confident that the workforce data set is in the hands of Dissident Republicans.

"It is now a planning assumption that they will use this list to generate fear and uncertainty as well as intimidating or targeting officers and staff.

“I won’t go into detail for operational reasons but we are working round the clock to assess the risk and take measures to mitigate it."

Earlier on Monday, North Belfast Sinn Féin MLA Gerry Kelly, who is also on the Northern Ireland Policing Board, said that a "number of documents" was posted on a wall facing the Sinn Féin's office on Falls Road in Belfast.

"There was a photograph of myself and there was a statement saying, in large writing, 'Gerry, we know who your mates are now,'" Kelly said on Monday.

"And under that then there was what appeared to be and what turned out to be a section of the leaked documents that were put out."

Kelly, who said he was coordinating with police regarding what he believed was a "deliberate threat," asserted: "I will not be intimidated."