"A multi-agency mission has gone this morning from the Turkey side across the border crossing... It's largely an assessment mission," the World Food Program's Syria director, Kenn Crossley, told AFP in Geneva.
The delegation comprised deputy regional humanitarian coordinator David Carden and Sanjana Quazi, who heads the UN's Office for the Coordination of Humanitarian Affairs (OCHA) in Turkey.
They visited a WFP center in Sarmada, near the Turkish border, and held a 40-minute meeting with officials at the Bab al-Hawa crossing - the only transit point on the Turkish border for U.N. aid deliveries to rebel-held areas.
Before the quake struck, almost all of the humanitarian aid for the more than four million people living in rebel-controlled areas was delivered from Turkey through that crossing.
Activists and emergency teams in the northwest have decried the UN's slow response to the quake in rebel-held areas, contrasting it with the planeloads of humanitarian aid that have been delivered to government-controlled airports.
On a visit to the Turkish side of the Bab al-Hawa crossing on Sunday, during which he met Syrian rescue teams, UN relief chief Martin Griffiths admitted that the world body had "so far failed the people in northwest Syria".
Griffiths also visited government-controlled areas devastated by the earthquake.