New Delhi, May 27 -- Britain and its allies risk losing a conflict in cyberspace against adversaries such as Russia unless citizens, corporations and governments treat cybersecurity with much greater urgency, a U.K. spy chief is warning.

Anne Keast-Butler, director of the communications intelligence agency GCHQ, will warn Wednesday that Moscow is "relentlessly targeting critical infrastructure, democratic processes, supply chains and public trust" in Britain and Europe. In a speech at a World War II code breaking center near London, she will accuse Russia of stealing technology and plotting sabotage and assassination attempts.

Keast-Butler plans to say that rapid advances in artificial intelligence mean that "the ground beneath our feet...