"It sounds like Erdogan is daydreaming when he says Afrin will fall tonight", Redur Xelil, the spokesman of the US-backed forces, said on Wednesday.
The head of Russia's military General Staff and the head of the U.S. Joint Chiefs of Staff discussed the Syrian crisis, including the situation in besieged eastern Ghouta, the Russian defence ministry also said on Tuesday.
Afrin city is the key target in Turkey's seven-week operation Olive Branch launched on January 20 and aimed at ousting the Kurdish People's Protection Units (YPG) from the Afrin region of northern Syria.
Turkish President Recep Tayyip Erdogan said on Wednesday that he hopes the northwestern Syrian city of Afrin will be liberated from terrorists "by this evening".
Turkey had warned the Syrian government against coming to the aid of the Kurdish militia which Ankara considers "terrorists" and aligned with Kurdish insurgents inside Turkey.
Recapturing the enclave would mark one of the most significant victories for President Bashar Assad in the seven-year civil war. The conflict has torn the country apart.More news: Where to get deals for National Pi Day
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While the USA and other imperialist powers denounce the Syrian offensive against armed groups in Ghouta as a violation of the cease fire ordered by the UN Security Council, Damascus and Moscow argue that they are fighting terrorist groups not protected by the ceasefire.
Russian Federation intervened in Syria in 2015 at Assad's request, helping him overcome a 2011 uprising sponsored by the West, Turkey and Gulf Arab states.
State-run Syrian TV broadcast footage showing a group of men, women and children it says left the town of Madyara after it was captured by Syrian troops on Sunday.
The largest rebel group in eastern Ghouta, the Army of Islam, said it had reached an agreement with government-allied Russian forces to evacuate the wounded from the enclave. He said government forces have seized local cemeteries, forcing residents to bury their dead elsewhere.
Government forces have recently split the enclave in two and cut off the towns of Douma and Harasta.
The operation has reportedly killed more than 1,100 civilians since it was launched in mid-February.