The secret services of a Nato country is "highly likely" to have been behind the assassination of ambassador Andrei Karlov, claimed a top ally of Vladimir Putin.
Senior senator Frantz Klintsevich, deputy chairman of the Russian upper chamber's defence and security committee, said: "It was a planned action.
"Everyone knew that he was going to attend this photo exhibition.
"It can be Isis, or the Kurdish army which tries to hurt Erdogan.
"But may be - and it is highly likely - that representatives of foreign NATO secrets services are behind it.
"What has happened is a true provocation, a challenge.
"It is a challenge for Russia."
The senator is a member of the ruling council of United Russia party, Putin's vehicle of power.
The Russian Foreign Ministry vowed that terrorism would not win after the assassination of the Russian ambassador in Turkey.
- AP