A top-secret communications system used by criminals to trade drugs and guns has been "successfully penetrated", says the National Crime Agency.
The NCA worked with forces across Europe on the UK's "biggest and most significant" law enforcement operation.
Major crime figures were among over 800 Europe-wide arrests after messages on EncroChat were intercepted and decoded.
More than two tonnes of drugs, several dozen guns and £54m in suspect cash have been seized, says the NCA.
While the NCA was part of the investigation, it was initiated and led by French and Dutch police, and also involved Europol - the EU agency for law enforcement cooperation.
Wil van Gemert, deputy executive director of Europol, told a press conference in the Hague that the hacking of the network had allowed the "disruption of criminal activities including violent attacks, corruption, attempted murders and large-scale drug transports".
https://www.bbc.co.uk/news/uk-53263310