The group Doctors Without Borders called Sunday for the "urgent scaling up" of earthquake aid to northwest Syria as it delivered a convoy laden with emergency assistance.

Aid has been slow to reach Syria's rebel-held areas since the February 6 quake killed a combined total of more than 44,000 people across Turkey and Syria.

"An urgent increase in the volume of supplies is needed to match the scale of the humanitarian crisis," said the French aid group Doctors Without Borders (MSF).

It charged that supplies "currently fail to even match pre-earthquake volumes".

"Aid is trickling in in negligible amounts for the moment," said Hakim Khaldi, MSF's head of mission in Syria. "We emptied our emergency stocks in three days."

"According to UN data, five days after the earthquake, only 10 trucks had entered" rebel-held areas of Syria through the Bab al-Hawa crossing from Turkey, MSF said.

It added that "in the 10 days following the earthquake, the number of trucks that crossed the border into northwest Syria was lower than the average weekly number for 2022".

A convoy of 14 trucks laden with 1,269 tents and winter kits sent by MSF had arrived in Syria through the Al-Hammam crossing in the Afrin area on Sunday.

"The delivery was arranged outside of the United Nations cross-border humanitarian mechanism," the group said.

Activists and emergency teams in Syria's northwest have decried a slow UN response to the quake in rebel-held areas, contrasting it with the planeloads of aid that have been delivered to government-controlled airports.

Before the quake struck, almost all of the crucial humanitarian aid for the more than four million people living in rebel-controlled areas was being delivered through just one crossing, Bab al-Hawa.

The UN announced on Monday that Syrian President Bashar al-Assad had agreed to open two more border crossings from Turkey to northwest Syria to allow in aid.

Since the quake, the UN has sent more than 170 aid trucks to northwest Syria.

The conflict in Syria started in 2011 with the brutal repression of peaceful protests and escalated to pull in foreign powers and global jihadists.

Nearly half a million people have been killed, and the conflict has forced around half of the country's pre-war population from their homes.