They have drafted in Army Technical Officers to assist in the search of a number of properties in the New Lodge area.
Two people have been arrested and the investigation is ongoing.
ATO are using a remote control robot unit to help in the search.
A PSNI spokesman said: “Police have arrested two people following a search of premises in North Belfast today, Thursday 14 July.
“A 28-year-old man and a 29-year-old woman have been taken to the serious crime suite at Musgrave Police Station for questioning.
“Searches are still ongoing in the New Lodge area and ATO is in attendance.
“There are no further details.”