The investigation into the assassination of Russia’s ambassador to Turkey Andrei Karlov and successful completion of the operation in Syria’s Aleppo were in the focus of a telephone conversation between Presidents Vladimir Putin of Russia and Recep Tayyip Erdogan of Turkey, the Kremlin press service said on Friday.

"The Turkish president informed Putin about the investigation into the assassination of Russian Ambassador to Turkey Andrei Karlov. The sides noted close cooperation between Russian and Turkish law enforcers and security services on that matter," the press service said.

On December 19, Russian Ambassador to Turkey Karlov, who had been invited to the opening ceremony of a photo exhibition, was shot during an attack and later died in a hospital of the sustained wounds. Three more people also sustained gun wounds during the attack, according to various media reports.

Local news outlets reported that the suspected assailant was killed by law enforcers. The gunman was identified as Mevlut Mert Altintas, a former special task police officer born in 1994.

The Russian president said earlier that those seeking to harm the Russian-Turkish relations might be behind this crime.

Apart from that, the sides continued the discussion of the Syrian settlement problem.

"Both sides expressed satisfaction over the successful completion of the operation in Aleppo, which has created favorable conditions for the launch of a peace process envisaging cessation of hostilities across Syria and transition to political settlement," the Kremlin said.

Russian Defense Minister Sergey Shoigu told the president earlier that the operation on the evacuation of militants from Aleppo had been completed and now Syria has all the conditions to launch talks on complete ceasefire. The minister said the operation was conducted "in close contacts with colleagues from Turkey and Iran." Putin, in turn, said Aleppo’s liberation was a major step towards normalization in Syria and in the region in general.