Russia's Federal Security Service (FSB), police and national guard in Moscow have been put on higher alert due to intelligence that there is a threat of a sabotage attack from Ukraine, Russia's state RIA news agency reported on Tuesday.

During the four-year war between Russia and Ukraine, both sides have carried out attacks far behind the front lines, using drones and sabotage units to carry out killings and attack critical infrastructure.

RIA said that the FSB, the main successor to the KGB, had received intelligence that Ukraine planned acts of sabotage and attacks on "government officials, military personnel of the Russian Defence Ministry and law enforcement officers."

Lieutenant General Vladimir Alexeyev, deputy head of Russia's GRU military intelligence service, was shot three times in February with a Makarov pistol equipped with a silencer in an apartment block on the Volokolamsk highway in northern Moscow. He survived the attack.