The agency said Filiponenko was eliminated in an early morning explosion.
Ukraine's military spy agency claimed responsibility for the assassination of a Russia-backed lawmaker with a car bomb in the occupied eastern city of Luhansk on Wednesday, an operation it said it conducted with local resistance forces.
Mikhail Filiponenko, a lawmaker in a Russia-installed local assembly, had been active in Luhansk's pro-Russian separatist movement since 2014. He had served as one of the top commanders in the army of the so-called Luhansk People's Republic.
The agency said Filiponenko was eliminated in an early morning explosion. He died at the site, it added on Telegram messenger.
It accused him of organising dungeons for civilians and prisoners of war in Luhansk region.
"Filiponenko himself brutally tortured people," agency said, giving no details.
In September, Filiponenko was elected to the regional parliament in a vote that drew widespread international condemnation.
Bomb blasts targeting senior Russian-installed officials in occupied parts of Ukraine have been a regular occurrence since Russia ordered tens of thousands of troops into Ukraine in Feb. 2022.
Luhansk is one of four Ukrainian regions Russia claims to have annexed since the start of its invasion, something Kyiv and its Western allies strongly reject.
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