The death toll from powerful earthquakes that devastated areas of Turkey and Syria has topped 40,000, according to figures collated by authorities in the two countries and other sources, as the United Nations began transporting relief materials through a new border crossing to Syria.

"The scale of this disaster is one of the worst in recent memory," U.N. Secretary General Antonio Guterres told reporters at the international body's headquarters in New York on Tuesday, citing the need to boost aid to those in violence-torn areas of Syria.

"The human suffering from this epic natural disaster should not be made even worse by manmade obstacles -- access, funding, supplies," Guterres said.

He added that the United Nations is launching an appeal for $397 million in humanitarian aid for quake-affected people in Syria, calling on member countries to make contributions.

Search and rescue operations continue on the rubble of a collapsed building in Adiyaman, Turkey, on Feb. 14, 2023, after a strong earthquake hit the country on Feb. 6. (Anadolu Agency/Getty/Kyodo)

The World Health Organization said it estimates a total of 26 million people need humanitarian assistance in Turkey and Syria, which were jolted by the quakes on Feb. 6.

According to the United Nations, 11 trucks carried fuel, blankets and mattresses into Syria through the additional border crossing with the consent of the Syrian government led by President Bashar al-Assad.

As more debris has been removed and more temporary shelters have been set up, search and rescue workers discontinued operations in some areas in Turkey.

Hans Kluge, the WHO's regional director for Europe, said Tuesday that there were "growing concerns over emerging health issues linked to the cold weather, hygiene and sanitation, and the spread of infectious diseases -- with vulnerable people especially at risk."

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