UKRAINE’S premier Volodymyr Groysman has accused Russia of being behind the killing in Kiev of the Russian journalist Arkady Babchenko.
"I am confident that the Russian totalitarian machine did not forgive him his honesty and principled stance," the prime minister posted on Facebook.
A Kremlin critic, Babchenko was gunned down outside his apartment on yesterday (Tuesday).
Russia has called for an investigation but said "bloody crimes" had become routine for the "Kiev regime".
Relations between Russia and Ukraine remain tense following Russia's annexation of Crimea in 2014 and the seizure of parts of eastern Ukraine by pro-Russian forces.
Babchenko, 41, was found bleeding at the entrance to his block of flats by his wife and died in an ambulance.
He was reportedly shot several times in the back.
Ukrainian lawmaker Anton Herashchenko said the journalist had gone out to buy some bread, and that the killer was waiting for him.
Kiev police chief Andriy Kryshchenko told local media they suspected Babchenko was killed because of his "professional activities"
In his last Facebook post just hours before the attack, Babchenko recalled a lucky escape four years ago - exactly to the day.
He wrote that he had planned to fly with Ukrainian soldiers on a helicopter to the war zone in Ukraine's east.
He was not allowed on board, because there was not enough space. The helicopter was shot down by pro-Russian rebels, leaving 14 people dead.
"I was lucky. A second birthday, it turns out", Babchenko wrote.
In his reaction, the Ukrainian prime minister referred to Babchenko's last Facebook post.
"This is the last post of Arkady Babchenko. Ten hours ago he wrote about his second birthday. And then they killed him.
"I am confident that the Russian totalitarian machine did not forgive him his honesty and principled stance. He was a true friend of Ukraine who told the world the truth about Russian aggression."
Groysman added: "The killers should be punished."