Turkish Prime Minister Ahmed Davutoglu has slammed Russia for bombing moderate rebels and civilians in Syria, arguing that Moscow's aerial campaign has boosted the Islamic State group.

Davutoglu told members of his ruling Justice and Development party that Russia has mostly been "targeting moderate opposition groups and civilians," and that IS militants have become "stronger in areas where opposition groups lost power."

The prime minister condemned what he said was a Russian Air Force attack in the Syrian town of Idlib on Dec. 20, an incident that killed more than 40 people, according to early reports.

Relations between Ankara and Moscow soured last month after the Turkish army downed a Russian jet on the Syrian border, an incident that led to the death of a Russian pilot and rescue marine.