Foreign Minister Mevlüt Çavuşoğlu and U.S. Secretary of State John Kerry discussed Syrian ceasefire and humanitarian aid deliveries to the war-torn country in a phone call on Friday.

The two leaders agreed that the importance of delivering aid to Syrian civilians while the ceasefire is still under process. Çavuşoğlu also expressed Turkey's concern over the Assad forces' reported violations of the truce.

On Wednesday, U.S. Secretary of State John Kerry and his Russian counterpart, Sergey Lavrov, agreed to a 48-hour extension of the cease-fire, which first came into effect on Monday.

A London-based watchdog said Thursday that the Assad regime and its allies have violated a cease-fire that came into effect in Syria earlier this week a total of 28 times.

However, Russia, a key backer of Assad, said it was ready to extend the truce set to expire later Friday by 72 hours, despite accusing the United States and opposition of not fulfilling the deal.