LONDON — Britain is facing a “staggering rise” in attempts at assassination, sabotage and other crimes on U.K. soil by Russia and Iran, as the two states recruit criminals to “do their dirty work,” the head of Britain’s domestic intelligence agency said Tuesday.

MI5 Director General Ken McCallum said his agents and police have tackled 20 “potentially lethal” plots backed by Iran since 2022 and warned that it could expand its targets in the United Kingdom if conflicts in the Middle East deepen.