"As a result of a complex of operational and search measures, the Russian FSB prevented an attempt by Ukrainian special services to commit a sabotage and terrorist act at an oil and gas facility that supplies energy to Turkey and Europe," the FSB said in a statement.
The security forces detained a man recruited by the Ukrainian security service, the statement read, adding that four accomplices of the Ukrainian special services, citizens of Russia, who provided the preparation of the sabotage act, were also detained.
The FSB did not disclose other details of the operation and the identity of the detainees.
Earlier in September, Russia's Federal Security Service had prevented a series of terrorist acts against the authorities of the Kherson Region and Crimea, and obtained data on an operation conducted by foreign security services.