Turkey-Russia relations stand on shaky ground after the assassination of the Russian ambassador in Ankara.

Moscow distanced itself from Turkey’s claim that that followers of Muslim cleric Fethullah Gulen were behind the killing. Turkey’s Foreign Minister told US Secretary of State John Kerry that Gulenist supporters were behind the killing. Ankara has also accused Gulen of orchestrating the failed coup in July, a charge denied by the US-based cleric.

Mevlut Mert Altintas shouted ‘don’t forget Aleppo’ after killing Andrei Karlov at an art gallery on Monday, before he was shot dead.

Turkish and Russian investigators are currently working together on the inquiry. On Wednesday, Kremlin spokesperson Dmitry Peskov said it was too early to draw any conclusions when questioned about the Gulen claim, but added that the murder was a blow to the country’s prestige.

The comments came as Russian state media sources ran reports that jihadist group Jabhat Fateh al-Sham (formerly the Al-Nusra front) had claimed responsibility for the attack. However, the authenticity of the letter circulated online has not been confirmed.

On Tuesday, Vladimir Putin said that Karlov’s murder aimed to strain ties between the countries, and also derail Moscow’s attempts with Iran and Turkey to find a solution to the crisis in Syria. A meeting of the three countries foreign ministers went ahead as planned on Tuesday.

Amid the diplomatic tangle, Karlov’s body has been returned to Russia and the funeral will take place on Thursday. Putin has postponed his end-of-year press conference to attend and posthumously appointed him a Hero of Russia, the country’s top honour.