MOSCOW, Dec 26 — Russia's Federal Security Service (FSB) said today that it had foiled several plots by Ukrainian intelligence services to kill high-ranking Russian officers and their families in Moscow using bombs disguised as power banks or document folders.

Ukraine's SBU intelligence service killed Lieutenant General Kirillov, chief of Russia's Nuclear, Biological and Chemical Protection Troops, on Dec 17 in Moscow outside his apartment building by detonating a bomb attached to an electric scooter.

An SBU source confirmed to Reuters that the Ukrainian intelligence agency had been behind the hit. Russia said the killing was a terrorist attack by Kyiv and vowed revenge.

"The Federal Security Service of the Russian Federation has prevented a series of assassination attempts on high-ranking military personnel of the Defence Ministry," the FSB said.

"Four Russian citizens involved in the preparation of these attacks have been detained."

The FSB, the main successor to the Soviet-era KGB, said that the Russian citizens had been recruited by the Ukrainian intelligence services.

One of the men retrieved a bomb disguised as a power bank in Moscow that was to be attached with magnets to the car of a one of the defence ministry's top officials, the FSB said.

Another Russian man was tasked with reconnaissance of senior Russian defence officials. One plot involved the delivery of a bomb disguised as a document folder, the FSB said. — Reuters