Turkey's foreign minister has called for an immediate ceasefire in Syria, describing the situation in Aleppo as critical and saying President Bashar al-Assad is unfit to rule.
Asked about Assad at a news conference in Beirut on Friday, Mevlut Cavusoglu said it was undeniable the Syrian leader was responsible for 600,000 deaths and somebody with that record should not be running a country.
NATO member Turkey is a major backer of rebels fighting to oust Assad.
The rebels have come under siege in eastern Aleppo after rapid advances by Syrian government forces in recent days, bringing them to the brink of a major defeat.
Cavusoglu said Turkey was speaking with Assad's allies Russia and Iran, as well as with Syria and Lebanon, about trying to find a solution in Syria.
Turkish President Recep Tayyip Erdogan and Russia's Vladimir Putin have spoken by phone at least three times during the past week about Syria, while Russian Foreign Minister Sergei Lavrov met Cavusoglu in Turkey on Thursday.
Cavusoglu said after that meeting that Moscow agreed on the need for a halt to fighting and the provision of aid in Aleppo, but deep divisions remained between them over the conflict.