The UN Security Council failed to find a consensus on prolonging cross-border humanitarian aid to Syria on Friday after Russia and China vetoed an extension and members rejected a counter proposal by Moscow.
Without an agreement, authorization for the transport of aid to war-torn Syria, which has existed since 2014, expired Friday night.
Germany and Belgium were working on a final initiative to save the effort, with hopes of bringing it to a vote this weekend.
"We are ready to work round the clock, and call on others to think of the millions of people in Syria waiting for the Security Council to decide their fate," said German Ambassador Christoph Heusgen, who holds the rotating presidency of the Security Council this month.
After Moscow and Beijing wielded vetoes for a second time this week, only three countries joined Russia in backing its proposal to cut the number of aid transit points from two to one.
China supported Russia, but seven countries including the United States, Britain, France, Germany and Belgium voted against, with four abstentions.
An attempt by Russia to pass a similar resolution also failed earlier this week.
The NGO Oxfam had warned that stopping cross-border aid would be "a devastating blow to the millions of Syrian families who rely on this aid for clean water, food, health care and shelter."
Thirteen countries voted in favor of an earlier German-Belgian draft, but Moscow and Beijing opposed the extension because they favor a more limited proposal.
European countries and the US want to maintain two crossing points on the Turkish border -- at Bab al-Salam, which leads to the Aleppo region, and Bab al-Hawa, which serves the Idlib region.
The UN authorization allows the body to distribute aid to displaced Syrians without needing permission from Damascus.
Russia and China argue that the UN authorization violates Syria's sovereignty, and that aid can increasingly be channeled through Syrian authorities.
The latest proposal by Russia, which claims to want continued aid for the insurgent Idlib region, would have kept only the Bab al-Hawa access point open, and for one year.
Moscow claims that more than 85 percent of current aid goes through Bab al-Hawa and that the Bab al-Salam entry point can therefore be closed.
Western countries oppose it, with the US having described two entry points as "a red line."
In January, Moscow, Syria's closest ally, succeeded in having the crossing points reduced from four to two and in limiting the authorization to six months instead of a year.
- 'Dark day' -
According to Washington's ambassador to the UN, Kelly Craft, keeping only one border crossing open would cut off 1.3 million people living north of Aleppo from humanitarian aid.
Another diplomat noted that "if the authorization is renewed a few days late, it is not the absolute end of the world. It suspends the convoys for a few days, it does not put them in danger."
For the UN, keeping as many entry points open as possible is crucial, particularly given the risk of the coronavirus pandemic, which is spreading in the region.
In a report in June, UN Secretary-General Antonio Guterres called for a one-year extension of the aid to include the two current access points.
When asked Thursday if the UN would be satisfied with a single entry point into Syria, body spokesman Stephane Dujarric said: "We need more aid to go through the border. We do not need less to go through."
David Miliband, president of the International Rescue Committee, called it a "dark day" for Syrian civilians and the UN.
He added it "defies logic or humanity to dismantle a system designed to bring life-saving aid to Syrians in the form of food, health supplies, vaccines, and now critical COVID-19 provisions."