GENEVA - The Office for the Coordination of Humanitarian Affairs (OCHA) said Tuesday that aid deliveries set to reach besieged and hard-to-reach areas in war-torn Syria have been temporarily put on hold following an airstrike on a UN/Syrian Arab Red Crescent convoy Monday.

"As an immediate security measure, other convoy movements in Syria have been suspended for the time being," OCHA spokesman Jens Laerke told the press.

According to reports, 18 out of 31 trucks carrying life-saving supplies were destroyed by warplanes in Urum al-Kubra, northwest of Aleppo.

The evening-attack resulted in at least one senior humanitarian official working for the Syrian Arab Red Crescent being killed as well as civilian casualties and severe damage to key infrastructure including a hospital.

A UN spokesperson said the convoy had received clearance from all required parties to deliver critical supplies of food, medical supplies as well as non-food items including blankets and clothes to some 78,000 people in Big Orem.

"This is a very, very dark day for humanitarians in Syria and across the world. I think there has been a moment of shock and frankly disgust by this attack," Laerke said.

"At this point, we remain committed and undeterred to continue to the best of our ability to help all Syrians in needed," he added.