Police are continuing to quiz a man arrested in Sunderland in connection with a major weapons haul in Northern Ireland.
The 45-year-old was detained on Wearside yesterday morning.
The Police Service of Northern Ireland today confirmed he remained in custody.
Detective Inspector Adrian Brown, from the Police Service of Northern Ireland (PSNI), said the arrest operation involved officers from across the UK, including the Northumbria force.
He said: “Officers from PSNI Serious Crime Branch, investigating an arms and explosives find in West Belfast on September 18, assisted by officers from North East Counter Terrorism Unit and Northumbria Police, have arrested a 45-year-old man in Sunderland.”
The arrest came after more than half a kilogram of Semtex explosives, two handguns, more than 200 rounds of ammunitions and two detonators were recovered when police raided a property in the Ballymurphy area of Belfast on Friday.
The PSNI said the search was part of an investigation into violent dissident republican activity.
The threat level from dissidents opposed to the peace process in Northern Ireland remains severe.
Unionist politicians have described the discovery of Semtex, a plastic explosive used by the Provisional IRA during the 1980s and 1990s, as deeply concerning.
Former Libyan dictator Colonel Gaddafi sent three shipments of Semtex to the PIRA and victims have long been campaigning for compensation from any new Libyan Government.
The Northern Ireland Select Committee at Westminster is also conducting an inquiry into the role of the UK Government in seeking financial redress for those affected by explosives supplied by the Gaddafi regime.
It is believed the quantity of Semtex found in West Belfast would have been sufficient to make three under-car booby trap bombs.
The PSNI said no further details would be released about the arrest in Sunderland at this stage.