Known as EncroChat, it was used on bespoke mobile phones that were designed to be secure against police infiltration and examination.
"There were 60,000 users worldwide and around 10,000 users in the UK," said the UK's National Crime Agency (NCA) of the ongoing raids. "The sole use was for coordinating and planning the distribution of illicit commodities, money laundering and plotting to kill rival criminals."
The secretive communications network was cracked in April, after agencies in France and the Netherlands cracked into the EncroChat app installed on mobile phones which was supposed to provide security against government infiltration and examination. Once the app was cracked, agencies began monitoring the gangsters' "every move" according to the NCA.