Wounded Syrians receive medical care at a makeshift clinic in the rebel-held town of Douma, on the eastern outskirts of Damascus, on Sept. 26, 2017 following reported air strikes by Syrian government forces. (Xinhua/AFP)

UNITED NATIONS, Oct. 6 (Xinhua) -- A UN official said on Friday that September marked the "deadliest month" of the year for Syrians as heavy air attacks caused high numbers of civilian casualties.

Hospitals, ambulances, schools and displaced people escaping violence are being routinely targeted by airstrikes in Syria, resulting in high numbers of deaths and injuries, said Panos Moumtzis, the United Nations Regional Humanitarian Coordinator for Syria Crisis.

"I am appalled by reports of high numbers of civilian casualties due to heavy air attacks in Syria," said Moumtzis in a news release issued by the UN Office for the Coordination of Humanitarian Affairs (OCHA).

"September was the deadliest month of 2017 for civilians with daily reports of attacks on residential areas resulting in hundreds of conflict-related deaths and injuries," he said.

This week, airstrikes on Raqqa City killed dozens of people and injured many others while some 8,000 others remain trapped there.

Between Sept. 19-30, airstrikes on residential areas in Idlib killed at least 149 people, the majority of whom were women and children.

"Attacks on medical facilities are depriving people in need of their right to life-saving medical care," stressed Moumtzis.

Schools and hospitals in Idlib have been forced to close for fear of being targeted. Three explosions in Damascus city caused the death of 20 people and injured 15 more. Civilian casualties were also reported in Rural Damascus, Hama, Aleppo and Deir-ez-Zor.

"I would like to praise the phenomenal work carried out by humanitarian workers and in particular national staff," he said, noting that rescue workers on a daily basis risk their lives to help others.

"The UN calls on all parties to the conflict to immediately take all measures to protect civilians and civilian infrastructure throughout Syria," Moumtzis said.