"The exposed intelligence operations were organised by the head of the Ukrainian military intelligence department, located in the city of Kherson, Maj. Oleg Akhmedov, born in 1975", the FSB said in a statement.
The FSB specified it had thwarted the activities of the Ukrainian Defence Ministry's Chief Directorate of Intelligence, aimed at staging terror attacks, stealing state secrets and recruiting Russians.
The FSB specified that the group of agents recruited by Akhmedov included a Russian female military officer, suspected of providing Ukrainian intelligence with top secret information in the period between 2017 and 2018, and a Ukrainian citizen, suspected of spying under instruction of Ukrainian special services.
"The Russian FSB's Investigative Directorate has initiated criminal cases on state treason and espionage", the statement read on.
The woman has been put under house arrest due to the fact that she has children of minority age, and the Ukrainian citizen has been put in custody, the FSB added.