Dutch police shut down an industrial-sized cocaine lab, seized more than 3.4 million euros (US$4.1 million) in cash and arrested nine suspects during several raids in Rotterdam, law enforcement reported on Friday.

Four users of the encrypted communications platform EncroChat have been sentenced for drug trafficking in the U.K., following a National Crime Agency (NCA) investigation stemming from the decoding of messages on the once-secured phone system.

British authorities said they have seized drugs worth 4.3 million pounds (nearly US$6 million) from suspected members of a criminal network that sold MDMA, commonly known as ecstasy, amphetamines and other narcotics on the dark web.

Dutch police arrested six men after they discovered six containers that were turned into prison cells and the seventh into a torture chamber equipped with a dentist chair with belts on arms and foot supports, pliers, knives and other utensils meant to cause pain.