Russia said Monday that it had detained three of its citizens on suspicion of attempting to assassinate a high-ranking Crimean official with a car bomb.

Several high-profile backers of Russia's assault on Ukraine and Moscow-installed officials since the conflict began in February 2022 have been targeted with assassination attempts.

The three suspects, identified only by their initials and last names, were found in possession of an improvised explosive device, Russia's FSB security service said.

The FSB said that the attempted attack had been "organised by the Security Service of Ukraine", and that the three suspects had been charged with terror offences.

AFP was not able to immediately verify the FSB's claim, and the FSB did not name which official had been targeted.

Ukraine does not typically claim responsibility for the killings of pro-Russian figures, both inside Russia and in parts of Ukraine occupied by Russian forces.

But it has openly threatened to hunt down individuals it calls "collaborators" and "traitors", including in Crimea, which was annexed by Russia in 2014.

A 23-year-old Russian man was separately detained on Monday for setting fire to a railway equipment cabinet in Moscow, allegedly on Ukrainian orders, state media reported.