LONDON — Three Bulgarian nationals based in Britain were convicted on Friday by a London jury of spying for Russia on what prosecutors said was “an industrial scale.”

The trio was accused of putting lives in danger as they acted on orders on behalf of Russian intelligence to carry out surveillance across Europe between 2020 and 2023.

Katrin Ivanova, 33, Vanya Gaberova, 30, and Tihomir Ivanov Ivanchev, 39, were convicted Friday at London’s Central Criminal Court after a trial that began…