Ukraine said Wednesday it was behind the assassination of a Russia-backed politician and former militia leader who died in a car bomb attack in eastern Ukraine.

Mikhail Filiponenko, a deputy in the pro-Moscow Lugansk regional parliament, was killed on Wednesday morning when an "unidentified explosive device" detonated under his 4x4, Russian investigators said earlier.

In a statement issued a few hours after the attack, Ukraine's military intelligence directorate said it had carried out a "special operation to eliminate" Filiponenko, working "jointly with representatives of the resistance movement."

Several high-profile backers of Russia's assault on Ukraine and Moscow-installed officials have been attacked since Russia launched its offensive last February -- though outright claims of responsibility by Kyiv are rare.

Filiponenko was a deputy in the Lugansk regional parliament and a former head of a Moscow-backed separatist militia set up in 2014 to fight against Kyiv.

Moscow-backed proxies in the Lugansk and neighbouring Donetsk regions of Ukraine launched a civil war in 2014 after a pro-European revolution in Kyiv.

Last year Russia claimed to annex Lugansk, along with three other Ukrainian regions, despite not having full control over them.

Earlier on Wednesday Russia's Investigative Committee published a video of forensics teams working at the site of the blast, showing a destroyed dark 4x4 car parked at the side of the road, with blood smeared across the driver's seat.

It said it had opened a criminal investigation.

The Russian-installed head of the region Leonid Pasechnik hailed Filiponenko as a "real man" and called his death a "heavy loss" in a post on social media.

Ukraine's military intelligence said it would continue to target "war criminals and collaborators" working with Russia.

It claimed Filiponenko had "personally and brutally tortured" civilians and prisoners of war, while in the Lugansk militia.

Several pro-Kremlin politicians and public figures have been targeted since Russia launched its assault on Ukraine in February 2022.

Last month Oleg Tsaryov, a pro-Kremlin politician that Moscow was reportedly lining up to lead a puppet government in Kyiv, survived being shot in his hotel complex on the annexed peninsula of Crimea.

Moscow has said Ukrainian secret services were behind that and several other attacks, including the car bombing of nationalist Darya Dugina outside Moscow last year and the bombing of military blogger Vladlen Tatarsky in a Saint Petersburg cafe in April.