Russian President Vladimir Putin said Monday the attack on Russian envoy was a "provocation" to undermine relations Turkey and Russia carry in Syria.
Putin's remarks followed the fatal shooting of Andrey Karlov, Moscow’s ambassador to Turkey, at an art exhibition in Ankara.
"Attack on Russian ambassador was a provocation against the good relations that Turkey and Russia carried out in Syria," Putin said and called for a 'strengthening' of the war against terrorism as a response to the assassination.
He also wanted to know who "directed" the killer.
Prime Minister Dmitry Medvedev said: "Russia will not leave it unpunished. Whoever has been involved in this organization would give an account for."
Medvedev said killing of an ambassador was a "serious" crime according to international law.
Meanwhile, Turkish Foreign Minister Mevlut Cavusoglu had a phone call with his Russian counterpart Sergey Lavrov, a Turkish diplomatic source said.
During the phone conversation, Cavusoglu strongly condemned the "heinous" attack and conveyed his condolences to Lavrov and Russian people, the source, who spoke on condition of anonymity due to restrictions on talking to media, said.
Cavusoglu said the attack was directed against Turkish-Russian "friendship".
Karlov was delivering a speech at the Contemporary Arts Gallery in the central Cankaya district when an assailant opened fire on the diplomat before shooting into the air, according to an Anadolu Agency correspondent who witnessed the shooting.
The envoy was seriously wounded and immediately rushed to a hospital where he was later pronounced dead.
Police special forces neutralized the attacker in an operation that lasted around 15 minutes.
Source: Anadolu Agency