Ukrainian Security Service (SBU) officials detained a large group of Russian resident spies in Kharkiv in August, SBU head Vasyl Hrytsak has said.

"A large station of Russian intelligence comprised of 18 people was detained in Kharkiv on August 17. Seven of them have already been notified of charges brought against them, and 16 searches have been conducted. They had carried out reconnaissance and sabotage activities in our territory," the SBU head said in an interview with the Priamy TV channel.

"The station's curator was involved with Russian intelligence, he controlled the group's activities in Ukraine from Belgorod," Hrytsak said.

In addition, the SBU is "documenting" another group engaged in similar activity, he said.