The main separatist leader in eastern Ukraine was killed in a bombing at a cafe in the centre of rebel hub Donetsk on Friday, becoming the most prominent victim from the Moscow-backed side in the four-year conflict.
Russian Federation is believed to have supplied a mobile Buk missile launcher that a team of worldwide investigators claims shot down a Malaysian passenger jet while flying over rebel territory in 2014, killing all 209 people aboard.
But an anonymous source told Interfax news agency that DPR's finance minister, Alexander Timofeev.
Alexander Zakharchenko was reportedly killed in an explosion.
Russian-backed rebels threw off Ukrainian central rule in an armed uprising after pro-Western leaders opposed by Moscow came to power in the Ukrainian capital, Kiev, in 2014.
Security forces arrested Ukrainians suspected of causing the blast.
Russia's Foreign Ministry had every reason to believe Kiev was responsible for Mr. Zakharchenko's death, ministry spokeswoman Maria Zakharova said on the Rossiya-24 (Russia-24) state-television station.
Zakharchenko's death shows that Kiev has chose to engage in a "bloody fight" and has passed up on its promises of seeking peace, she said.More news: John McCain Lies in State at U.S. Capitol for Final Farewell
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Ihor Huskov, chief of staff for Ukraine's Security Service, said Zakharchenko was killed as part of an internal criminal conflict among militants.
"Instead of abiding by the Minsk Agreements and seeking ways to resolve the internal [Ukrainian] conflict, the Kiev warmongers opted for a terrorist scenario, thus exacerbating an already tense situation in the region", she added.
Mr Zakharchenko, 42, had been leader since 2014, the year that parts of eastern Ukraine dominated by Russian Federation seceded, leading to a bloody struggle with government troops that continues sporadically today.
In a letter published on the Kremlin website, Putin said the separatist leader was "a true people's leader, a courageous and resolute man.in a hard time for his homeland, he stood up in its defence, assumed a huge personal responsibility, and led the people".
"He could have been taken out because of criminal schemes or maybe his Kremlin curators grew exhausted of him or the Ukrainians may have done it", said Igor Girkin, a former separatist commander.
Zakharchenko introduced Soviet-style military parades with tanks in Donetsk and usually wore military fatigues, despite his political role.
Putin issued a statement Friday praising Zakharchenko as a "courageous and decisive person, a patriot".