THE PSNI has sealed off part of the Buncrana Road in Derry.
The road has been sealed off at the Collon junction.
British Army Technical Officers arrived at the scene around lunchtime,
It is understood that a property at Maybrook Terrace is at the centre of the probe.
A number of items were taken away for further information after a property was search shortly after 9.15 am this morning.
Traffic diversions are in place.