Syrian army gains in Aleppo spark alarm

A senior UN official says Aleppo risks becoming a “giant graveyard” as the Syrian army offensive to retake the city is gaining momentum.

Speaking to a special Security Council session by video-link from London, UN aid chief Stephen O'Brien called for concrete measures to protect civilians.

“For the sake of humanity we call on -- we plead -- with the parties and those with influence to do everything in their power to protect civilians,” he said on Wednesday.

He called for "access to the besieged part of eastern Aleppo before it becomes one giant graveyard." 

A local council leader in east Aleppo also called for safe passage for desperate civilians, warning the UN would be "signing the death warrant of 250,000 people" if it failed to act.

"Let the civilians leave, protect the civilians, put in place a safe corridor so they can leave," Brita Hagi Hassan said after meeting French Foreign Minister Jean-Marc Ayrault.

The Syrian government and Russia set up humanitarian corridors for safe passage of civilians earlier this month but the plan failed after militants prevented residents from leaving by shelling the exit routes. 

On Wednesday, shells hit a militant-controlled area of eastern Aleppo as residents sought to leave, killing dozens of civilians. A London-based observatory which is sympathetic to militants accused the army of carrying out the shelling. 

The attack came after the so-called Syrian Observatory for Human Rights said more than 50,000 people had fled militant-held areas over the past few days.

It also came after government troops and allied fighters seized around 40 percent of eastern Aleppo where several militant groups backed by Turkey, Saudi Arabia and the West are holed up.