The UN mandate for the eight-year-long aid operation expires on Sunday. After negotiations yesterday evening that pitted Russia against the US and Britain, the 15-member council agreed to return today for further talks.

Russia only wants to renew the aid operation for six months and require the council to then adopt a new resolution to extend it for another six months, said Russia’s deputy UN ambassador Dmitry Polyanskiy.

“Six months ends in January, in the middle of winter, the worst time possible,” US ambassador to the UN, Linda Thomas-Greenfield, told reporters.

“A six month resolution does not provide the certainty and the confidence that the Syrian refugees require and the NGOs (aid groups) require in order to continue to plan for and provide for support,” said Thomas-Greenfield, who visited the Turkish border crossing last month to assess the aid operation.

An attempted compromise text, drafted by Ireland and Norway and circulated late yesterday, would renew the aid operation for one year and require the council to adopt a new resolution if the mandate is to be ended after six months.

Ireland’s UN ambassador Geraldine Byrne Nason told reporters she would continue working overnight and “hopefully be back in the morning with a solution.”

The Security Council vote on the cross-border aid operation has been a contentious issue for several years.

In 2014 the Security Council authorised humanitarian aid deliveries into opposition-held areas of Syria from Iraq, Jordan and two points in Turkey. But veto powers Russia and China have whittled that down that down to just one Turkish border point.

UN secretary-general Antonio Guterres appealed to the council last month to extend its approval of the aid deliveries from Turkey into northwest Syria, telling the body: “We cannot give up on the people of Syria.”