Russian media reports say a former leader of Russia-backed separatists in Ukraine's Luhansk region has died in Russia at the age of 46.
Reports say Valeriy Bolotov, a Luhansk businessman who acted as a separatist leader in the region in 2014, was found dead in his apartment in Russia on January 27.
There were conflicting reports about whether his apartment was in Moscow or outside the Russian capital.
There was no immediate confirmation of the cause of Bolotov's death, though Russian state media quoted sources as saying he died of a heart attack.
Several prominent separatists have died or been killed in murky circumstances, while others have survived assassination attempts.
Bolotov himself survived an attempted assassination during his time as a self-declared leader in Luhansk.
Infighting among the Russia-backed separatists has repeatedly bubbled into public view since their war against the Kyiv government's forces broke out in April 2014.
Despite significant evidence of Russia's involvement in eastern Ukraine, Moscow denies supporting the separatists with troops and weaponry.