International aid organisations have stepped up calls for civilians trapped in the flashpoint Syrian city of Qusayr to be evacuated, as rebel fighters faced a fresh assault from government forces.
UN agencies and the International Committee of the Red Cross (ICRC) appealed to both sides in the fighting to let the civilians, including an estimated 1,500 wounded, leave the embattled town.
Qusayr is normally home to about 30,000 people.
Britain on Saturday circulated a draft declaration at the UN Security Council, voicing "grave concern about the situation in Qusayr".
Russia, however, blocked the draft because the UN had failed to speak out when Qusayr was seized by rebels more than a year ago.
The regime’s military campaign on Qusayr started two weeks ago, in an attempt to regain control of the strategic city bordering Lebanon. It is believed that Hezbollah has sent an estimated 1,700 fighters to support the regime's assault.
On Sunday, government fighter jets launched 10 airstrikes on the rebel-held areas of the city, activists there told Al Jazeera.
Regime forces have recently captured the northern district of Arjun in Qusayr, leaving rebels little chance to escape.
While around 300 rebels managed on Friday to break through army lines near the village of Shamsinn, northeast of Qusayr - after losing 11 fighters - it was unclear if they could quell the advances of regime forces.
Activists said that escape routes for civilians have become unsafe. They reported this week that a a convoy of civilians seeking to flee Qusayr was attacked by Syrian forces.
UN emergency relief coordinator Valerie Amos and High Commissioner for Human Rights Navi Pillay said there was "an urgent need of immediate evacuation for emergency medical treatment".
But a humanitarian corridor could only be created if both sides agreed, Rupert Colville, a spokesperson Pillay , told Al Jazeera.
"Some of those wounded will clearly die if they don't get medical treatment," Colville said.
"There should be a ceasefire at least and they let the civilians and the wounded get out and also let some aid in as well. Civilians who stay behind will need food and water."
In Geneva, the ICRC called for restraint on all sides.
"Civilians and the wounded are at risk of paying an even heavier price as the fighting continues," Robert Mardini, the head of Middle East operations, said, adding that ICRC had already requested access to the town.
The control of Qusayr is essential for the rebels as it is their principal transit point for weapons and fighters from across the border in Lebanon.
It is also strategic for the regime because it is located on the road linking Damascus with the Mediterranean coast, its rear base.