The Ukrainian security service (SBU) says it has foiled a Russian plot to assassinate President Volodymyr Zelensky and other high-ranking Ukrainian officials.
Two Ukrainian government protection unit colonels have been arrested.
The SBU said they were part of a network of agents belonging to the Russian state security service (FSB).
They had reportedly been searching for willing “executors” among Mr Zelensky’s bodyguards to kidnap and kill him.
Other targets included military intelligence head Kyrylo Budanov and SBU chief Vasyl Malyuk, the agency added.
The group had reportedly planned to kill Mr Budanov before Orthodox Easter, which this year fell on 5 May.
According to the SBU, the plotters had aimed to use a mole to get information about his location, which they would then have attacked with rockets and drones.
One of the officers who was later arrested had already bought drones and anti-personnel mines, the SBU said.
SBU head Vasyl Malyuk said the attack was supposed to be “a gift to Putin before the inauguration” – referring to Russia’s Vladimir Putin who was sworn in for a fifth term as president at the Kremlin on Tuesday.
The operation turned into a failure of the Russian special services, Mr Malyuk said.
“But we must not forget – the enemy is strong and experienced, he cannot be underestimated,” he added.
The two Ukrainian officials are being held on suspicion of treason and of preparing a terrorist act.
The SBU said three FSB employees oversaw the organisation and the attack.
One of them, named as Dmytro Perlin, had been recruiting “moles” since before Russia’s full-scale invasion of Ukraine in February 2022.
Another FSB employee, Oleksiy Kornev, reportedly held “conspiratorial” meetings “in neighbouring European states” before the invasion with one of the Ukrainian colonels arrested.
Russian forces have reportedly been trying to kill Mr Zelensky since the start of the war.
Last month, a Polish man was arrested and charged with planning to co-operate with Russian intelligence services to aid a possible assassination of Mr Zelensky.