Ukraine says aide to prime minister was spying for Russia
Ukraine's security agency says it has detained a government official accused of spying for Russia.
Ukraine's Security Service, or SBU, said the suspect allegedly passed government secrets to his Russian handlers.
Ukrainian media reports identified the suspect as an aide to Prime Minister Volodymyr Groysman who accompanied him on foreign trips.
Mr Groysman thanked the SBU for its "vigilance and professionalism" on Facebook.
Prime Minister Theresa May said on a trip to Warsaw that she is aware of reports that an interpreter for Ukraine's premier who was photographed with her in Downing Street has been arrested on suspicion of being a Russian spy.
Russia and Ukraine have been in a tug-of-war following Moscow's 2014 annexation of Crimea and support for pro-Russia insurgency in eastern Ukraine.