People walk near heavily damaged buildings in the rebel-held city of Idlib in northwestern Syria on September 16, 2019
People walk near heavily damaged buildings in the rebel-held city of Idlib in northwestern Syria on September 16, 2019 AFP / Zein Al RIFAI

Sponsors of a UN Security Council resolution calling for a ceasefire in Syria's war-torn Idlib province urged Russia Thursday not to veto the "purely humanitarian" measure.

Speaking before a UN Security Council meeting on Syria, ambassadors of sponsors Belgium, Kuwait and Germany warned that the conflict could become the century's worst humanitarian crisis if the fighting persisted.

"The Council cannot, must not, let that happen," they said.

The resolution, which was to be put to a vote in the Security Council later in the day, says "all parties shall immediately cease hostilities to avoid a further deterioration of the already catastrophic humanitarian situation in Idlib Governorate, beginning at noon Damascus time on 21 September 2019."

During negotiations on the draft, Russia pressed unsuccessfully to include an exception for "anti-terrorist operations."

So Russia and China countered by presenting an alternative resolution, which also could be voted on during Thursday's session.

It specifies that the ceasefire would not apply to military operations against individuals, groups or entities "associated with terrorist groups."

Russia backs the Syrian regime of Bashar al-Assad, which has been conducting a bloody four-month-long campaign to wrest Idlib province from jihadist forces.

On Wednesday, UN Secretary-General Antonio Guterres joined the head of the International Committee of the Red Cross Peter Maurer in appealing for an end to air and artillery bombardments of Idlib, citing the devastating impact on civilians.

Belgium, Kuwait and Germany have taken a leadership role in the council in following the humanitarian situation in Syria, a role known in UN parlance as "penholders."

"As co-penholders of the humanitarian file for Syria in the Council, we would like to call upon all member states to vote in favor of our resolution," they said.

"Our draft resolution the Council will vote on today is a purely humanitarian one," they said, noting that half a million people have been displaced since the Idlib offensive began four months ago.