The U.K. Government Communications Headquarters (GCHQ), Britain’s secret eavesdropping agency, warns that ‘a number of [UK] Industrial Control System engineering and services organisations are likely to have been compromised’ following the discovery of ‘connections from multiple UK IP addresses to infrastructure associated with advanced state-sponsored hostile threat actors.’

The warning comes from a National Cyber Security Centre (NCSC) memo obtained by Motherboard and confirmed by the BBC. NCSC is part of the UK’s primary cyber intelligence agency, GCHQ.