Hundreds of humanitarian workers formed a human chain in northwest Syria Friday, urging the international community to keep open the only border crossing for aid into the rebel-held region.

"Humanitarian aid is a right, not a privilege," one sign held up by aid workers read, while others stood in a pattern on the road, so that the words "Save lifeline" was visible from the air.

A UN authorisation for aid to transit through the Bab al-Hawa border crossing from Turkey into Syria expires on July 10.

Aid organisations fear that Russia, a staunch ally of the Damascus regime, might block a United Nations Security Council vote to renew it for a year.

Wassim Bakir, from Syrian charity Banafsaj, said if cross border aid was blocked it would be a "humanitarian catastrophe".

Men and women lined up along a key highway leading to Bab al-Hawa, through which international organisations ferry in vital aid to the Idlib region.

Some three million people live in the jihadist-dominated region, more than half displaced by Syria's decade-long conflict.

"Closing Bab al-Hawa... means cutting off medicines and food for millions of civilians," another sign read.

For the past year, international organisations have been able to bring in medicine, food, blankets and Covid-19 vaccines through Bab al-Hawa without having to transit through Damascus.

Ireland and Norway, non-permanent members of the UN Security Council, have presented a draft resolution to keep the Bab al-Hawa crossing open for another year.

The resolution also proposes the reopening of a second crossing point, Al-Yarubiyah on the Iraqi border, to allow supplies to reach Syria's northeast.