A search and an arrest operation is underway in Derry this morning.
A 52 year old man was arrested in Creggan earlier under the Terrorism Act and will be questioned in Musgrave Serious Crime Suite by detectives.
A detailed forensic examination of a house is currently on-going as part of the investigation.
In a statement Detective Chief Superintendent Raymond Murray, said that detectives made the arrest as part of Operation Ledging.
This is a discrete, stand-alone strand of Operation Arbacia, looking specifically at the New IRA's bomb making activities as well as the group's storage of explosive devices and equipment.
Operation Ledging is one of a number of ongoing investigative elements relating to the activities of the New IRA.
Today's arrest and examination of a house has been described as a significant development, in a long term enquiry, into this aspect of the gang's activities.
Operation Arbacia has been described as a longer term investigation that will look into every aspect of the activities of the New IRA in its entirety and police say that this latest search and arrest proves that there are various operations complementing Operation Arbacia and today does not mark the end of them but rather a continuance.