"It's an operation that concerns tobacco importing that is linked to the Italian Mafia and aboriginal organized crime," said Sûreté du Québec Sgt. Joyce Kemp.
Police officers executed search warrants and arrests this morning on the island of Montreal and in Dundee, about 100 kilometres southwest of Montreal.
Dundee borders the Mohawk reserve of Akwesasne.
Quebec provincial police are leading the operation, with help from the RCMP and other municipal police forces on Montreal's South Shore.
Police could not confirm the number of arrests expected this morning.
Police are expected to release more information at a 10:30 a.m. news conference.