"The Russian Federal Security Service has detained a Russian citizen ... who was planning to commit a terrorist attack at the Trans-Siberian railway junction in the Sverdlovsk Region at the direction of the Main Directorate of Intelligence of the Ukrainian Defense Ministry. A criminal case has been initiated against the detainee," the FSB said in a statement.
The detainee confessed to the crime and is cooperating with the investigation, the statement read.
"As part of the investigation, [the authorities] seized the means of conspiratorial communication with the curator, a device for derailing trains, as well as money transferred to him by the Ukrainian intelligence for preparing and executing the crimes," the FSB also said.
The detainee's criminal activities are being documented, the security agency added.