Ireland, The United States and Norway called on the UN Security Council to extend an agreement to keep open a border crossing through which humanitarian aid reaches war-torn Syria's rebel-held northwest.
The Bab al-Hawa crossing from Turkey into Syria will close on July 10 unless it receives authorization to stay open for another year in a United Nations Security Council vote on Thursday.
"We cannot accept less than what we have today. And that's one border crossing for 12 months that's providing support for millions of Syrians," said the American ambassador to the UN, Linda Thomas-Greenfield, after a closed-door meeting on humanitarian assistance to Syria.
If an extension of the cross-border aid mechanism is vetoed, she warned, "the repercussions are obvious, people will starve to death."
Some three million people live in jihadist-dominated northwest Syria, more than half displaced by the country's decade-long conflict.
For the past year, international organisations have been able to bring in medicine, food, blankets and Covid-19 vaccines through the Bab al-Hawa crossing - the only crossing for aid into the region that bypasses Damascus.
Russia, which wields veto power at the council and is a staunch ally of the Damascus regime, may block the renewal, preferring to see the aid delivered across front lines from Damascus and arguing the existing crossing is used to supply arms to rebel fighters.
During the meeting, Moscow "maintained its position, which has been clear for a long time", a Russian diplomat told AFP, on condition of anonymity.
According to France's UN ambassador, Nicolas de Riviere, since the beginning of the year, 50 percent of requests to deliver humanitarian aid across front lines have been rejected by the Syrian regime.
Before the sit-down, Irish ambassador to the UN Geraldine Byrne Nason told reporters "we're hoping to see a successful renewal" of the cross-border aid mechanism, and warned of a potential "humanitarian catastrophe."
"We understand its politically sensitive, we're making a purely humanitarian case," she said.
Ireland and Norway, non-permanent members of the UNSC, presented a draft resolution in late June that seeks to keep the Bab al-Hawa crossing open for one year and to reopen a second crossing point, Al-Yarubiyah, which allows supplies to reach Syria's northeast from Iraq.
Norway's UN envoy Mona Juul said it was "incredibly important" to get the "maximum" assistance into Syria.
"It's a lot at stake, it's really a life and death issue for so many," she added.
Humanitarian organizations have been pleading for months for an extension of the UN authorisation.
Earlier this week, Concern Worldwide, GOAL, Trocaire, Oxfam Ireland and World Vision appealed to the Security Council to approve the reauthorisation of the crossing for at least another 12 months.
In addition to the Bab al-Hawa border crossing, they also called for the re-opening of the Al Yarubiyah and Bab-al-Salam crossings, which have been closed over the last year and a half.
In a joint statement the NGOs said: "If the last remaining border crossing is closed off after July 10th the work of the entire humanitarian community to provide timely life-saving assistance, could be in jeopardy and the consequences will be disastrous. This cannot be allowed to happen. Ireland, with Norway, has specific responsibility at the UN Security Council to convene consensus on the text of the resolution that protects cross-border aid."