A draft resolution co-sponsored by Germany, Belgium and Kuwait and supported by the U.N. humanitarian office would continue the delivery of aid through two crossing points in Turkey and one in Iraq.

A rival resolution from Russia, Syria's closest ally on the council, would extend deliveries only through the two Turkish crossings.

The current year-long mandate expires on Friday, and if it is not extended, the delivery of food, medicine and other essential items will stop. The Security Council is scheduled to vote on the rival resolutions Friday afternoon. Both drafts would extend the mandate for six months,

Diplomats said the five veto-wielding council members — the United States, Russia, China, United Kingdom and France — met four times since last week and were unable to reach a compromise on a draft resolution.

Since 2014, the Security Council has authorized the delivery of aid through four border crossings — Bab al-Salam and Bab al-Hawa in Turkey, Al Yarubiyah in Iraq, and Al-Ramtha in Jordan.

U.N. humanitarian chief Mark Lowcock told the Security Council in November that 4 million people across northern Syria are supported by U.N. cross-border humanitarian assistance.

He said the U.N. provided 1.1 million people with food through cross-border deliveries in October, double the number in January. Since 2014, he said, the United Nations has sent nearly 30,000 trucks of humanitarian assistance across the four border-crossings.

"There is no alternative to the cross-border operation," Lowcock said. "There is no Plan B."

"Without the cross-border operation, we would see an immediate end of aid supporting millions of civilians,"" he warned. "That would cause a rapid increase in hunger and disease. A lot more people would flood across the borders, making an existing crisis even worse in the region."

The cross-border issue initially came to a head on Dec. 30 when Russia and China vetoed a resolution that would authorize deliveries through three crossings, which was supported by 13 of the 15 Security Council members.

A rival resolution sponsored by Russia and China would have only two crossing points in Turkey. It was defeated because it failed to get the required nine "yes" votes for adoption.

At the time, Russia's U.N. Ambassador Vassily Nebenzia said cross-border aid was meant to be a temporary response to the eight-year Syrian conflict and the situation on the ground has changed.

He said the Jordan crossing point hasn't been used "for a lengthy period of time" and the volume through the Iraqi crossing "is insignificant ... and could be done from Syria." The Russian draft allows aid through the two Turkish crossings "where it remains necessary," Nebenzia said.

Russia joined the war in 2015, when the Syrian military appeared close to collapse. Since then, and largely because of Russia's blanket air support, the Syrian government has largely won the civil war militarily, and has retaken control of most of the country from rebel fighters.

But Germany, Belgium and Kuwait, backed by the U.S., Britain, France and other council nations, insist the Iraqi crossing point is also critical, especially for the delivery of medicine.

Their draft resolution, to be voted on Friday, is more streamlined than the defeated measure and addresses some concerns of Russia, including calling on U.N. humanitarian agencies "to improve monitoring of the delivery and distribution of United Nations relief consignments and their delivery inside Syria."

It also asks Secretary-General Antonio Guterres to conduct an independent review of U.N. humanitarian operations across borders and conflict lines within six months, including on whether the Jordanian crossing should be re-authorized.

Secretary-General Guterres echoed Lowcock in a report to the council in late December saying "the United Nations does not have an alternative means of reaching people in need in the areas in which cross-border assistance is being provided."

U.N. spokesman Stephane Dujarric said then that the humanitarian situation in northwest and northeast Syria is "horrific," stressing that "it would be markedly worse without the cross-border operation."

David Miliband, head of the International Rescue Committee which supplies aid to 1 million Syrians across the country, said in a letter to Security Council members Wednesday that with humanitarian needs intensifying in the last rebel-held stronghold in northwest Idlib and in the northeast, and with tensions escalating in the Middle East "the last thing the region needs is for the delivery of humanitarian aid to be compromised."

"Humanitarian aid in Syria is not just a lifeline to millions in need, it shores up stability," he stressed.