Russia staged a sombre memorial ceremony on Thursday for Andrei Karlov, the Russian ambassador to Turkey gunned down in Ankara on Monday by a man shouting "Allahu Akbar" and "Don't forget Aleppo".

Russia and Turkey have branded the assassination a failed attempt to derail a rapprochement between Moscow and Ankara which has seen them cooperate more closely over Syria, where they have backed different sides in the conflict.

Diplomats and family members gathered at the Russian Foreign Ministry, a looming Stalin-era skyscraper in central Moscow, to bid farewell to Karlov, who was 62.

TV footage showed Karlov's body lying in an open casket in the building's marble-clad lobby flanked by a uniformed honour guard as mourners, including Prime Minister Dmitry Medvedev and Foreign Minister Sergei Lavrov, approached to lay flowers.