The U.N. Security Council adopted a resolution Tuesday extending for six months a key humanitarian aid corridor to northwestern Syria, with the possibility of another six-month renewal in January.

The cross-border mechanism, first authorized in 2014, involves a crossing at Bab al-Hawa in northwestern Syria that millions in the country rely on for food, clean water and other humanitarian assistance. Three permanent council members -- Britain, France and the United States -- abstained from voting after having sought a one-year extension of the crossing, while the 12 others including permanent members China and Russia voted in favor.

File photo taken in April, 2021 shows the United Nations headquarters in New York. (Kyodo) 

While the resolution adopts the Russian demand of a six-month extension, it also requires the U.N. Secretary General to prepare "a special report on humanitarian needs in Syria" in December, a month before the mechanism is due to expire again.

It had been left to expire on Sunday as the council failed to reach an agreement, with Russia vetoing a resolution introduced by the West and a Russian-authored resolution gaining support only from Russia and China.

International aid groups expressed concern about the expiration of the mechanism during the winter months, when freezing temperatures and flash floods in the region are common.

The United Nations estimates that humanitarian needs in Syria have risen to their highest levels since the start of the civil war in 2011.

"We asked for a renewal of one year," U.N. Secretary General Antonio Guterres told a group of reporters on Tuesday. "The Security Council approved six months. But I strongly hope that after the six months it will be renewed."