The prosecutor-general of the Russian-backed self-proclaimed Luhansk People's Republic (LPR) in eastern Ukraine and his deputy were killed by a bomb blast at their offices on Friday, the head of the LPR administration said.
"Today, as a result of a terrorist act, Prosecutor-General of the LPR Sergei Gorenko and his deputy Ekaterina Steglenko were killed," Leonid Pasechnik said in a statement posted on the Telegram messaging app.
Other local officials and the emergency services had previously told Russian news agencies that a bomb had exploded at the offices of the prosecutor general.
Pasechnik blamed Kyiv for the attack and called Ukraine a "terrorist state" under its current leadership.
There was no immediate comment from Kyiv.
The blast comes in what Pasechnik described on Thursday as a "tense situation" for Russia and its proxies in eastern Ukraine, part of the territory Russia has prised out of Kyiv's control since launching an invasion in February.
Russian and Russian-backed forces seized control of the entire Luhansk province in the Donbas region of eastern Ukraine earlier in the campaign, but Kyiv's recent lightning offensive has pushed the fighting closer to the LPR borders claimed by the separatists. Russia recognises the LPR as an independent state.
After the attack, Pasechnik reissued a call for those living in the LPR to remain calm and said authorities had the situation "under control".
On Thursday, he had acknowledged that Ukrainian forces had secured "some successes" in their campaign and were continuing to mount attacks against Russian forces along the entire frontline of the conflict.
(Reporting by Reuters; Editing by Kevin Liffey)