ANKARA (Reuters) - Turkey was in contact with Iran, Russia and the United States on Wednesday to try and ensure the evacuation of civilians and rebel fighters from Syria's Aleppo, as air strikes and heavy shelling threaten to scupper a truce.
President Tayyip Erdogan accused Syrian government forces of breaking the truce he brokered on Tuesday with Russia, one of Syrian President Bashar al-Assad's main backers, but said Turkey was still trying to open a humanitarian corridor from the city.
Erdogan said he would speak later on Wednesday by phone with Russian President Vladimir Putin about the situation in Aleppo, which he described as "very fragile".
"The realisation of the ceasefire brokered by Turkey's intense efforts is perhaps the last hope for the innocent people in Aleppo," Erdogan told a meeting of local administrators in the presidential palace in Ankara.
"This humanitarian corridor must be opened immediately, and the evacuation of civilians from eastern Aleppo must be allowed at once. Assad is committing war crimes in eastern Aleppo, and we cannot remain silent to the assassinations by the regime."
Iran, another key Assad backer alongside Russia, was said to have imposed new conditions on the truce deal which were delaying its implementation.
Turkish Foreign Minister Mevlut Cavusoglu spoke to his Iranian and U.S. counterparts on Wednesday to try to keep the agreement on track. He was also due to speak to the Russian foreign minister.
"There was an understanding as of yesterday, and within that was first the evacuation of civilians ... We see that the regime and other groups are trying to prevent this," Cavusoglu told reporters.
Russia's defence ministry said that rebels in Aleppo had resumed fighting at dawn and Syrian government forces had repelled their attacks, Russia's Interfax news agency reported.
A senior Turkish official told Reuters earlier that the ceasefire deal was very fragile but not broken, despite the reports of attacks in the city.
Erdogan said preparations were complete for evacuees from Aleppo to come to the rebel-controlled Syrian province of Idlib west of Aleppo and to Turkey.
An aid convoy by Turkish humanitarian aid group IHH carrying flour, food rations and clothing left Istanbul for the Syrian border on Wednesday.
Deputy Prime Minister Mehmet Simsek said on Tuesday that Turkey, which is already home to around 2.7 million Syrians who have fled the country's civil war, would set up a tent city to accommodate up to 80,000 people fleeing Aleppo.
Additional reporting by Humeyra Pamuk in Istanbul; Writing by Daren Butler; Editing by Nick Tattersall and Ralph Boulton