Russia on Friday vetoed a UN Security Council resolution that would have extended cross-border aid to Syria by one year without Damascus's backing.

The authorization for aid deliveries across the Syrian-Turkish border at Bab al-Hawa, which has been in effect since 2014, is set to expire Sunday.

The aid is a lifeline for more than 2.4 million people in the northwestern Idlib region of Syria, under the control of jihadists and rebels.

Thirteen of the fifteen Council members voted in favor of the text. China, which often votes the same way as Russia, chose to abstain.

The vote had been due to be held Thursday but was scrapped following disagreement between Russia and the West.

Moscow is seeking a six-month extension. Sunday's deadline still leaves time for members of the Security Council to find common ground, observers note.

The vetoed text, proposed by Norway and Ireland, would have provided for a six-month extension until mid-January 2023, and then an additional six-month extension "unless the Council decides otherwise."

The extension would also be conditional on a "substantive report" by the secretary-general, including on the operation's transparency, progress on channeling aid across the front line, and progress on meeting humanitarian needs.

Nearly 10,000 trucks loaded with humanitarian aid passed through Bab al-Hawa last year, bound for the rebel-held Idlib region in northwestern Syria. It is the only crossing through which aid can be brought into Idlib without navigating areas controlled by Syrian government forces.

Moscow, an ally of Damascus, has curtailed a number of Western-backed measures in recent years.

It views the authorization as a violation of Syria's sovereignty, and believes the delivery of aid to the northwest region should only be carried out from Damascus across the front line.

Russia had hinted in recent months that it would oppose an extension, having already forced a reduction in the number of allowed border crossings.