Aleppo's White Helmets: We've less than 48 hours left

But with the imminent fall of rebel-held eastern Aleppo into Assad's hands, the heroic saviours of the civilians besieged by the bloody six-year war are now fearing for their lives.

The Russian-backed government forces are edging closer to where the volunteers operate, and they warn they have less than 48 hours left before they meet their fate.

"If we are not evacuated our volunteers face torture and execution in the regime's detention centres," the group said in a statement on Friday.

"We need urgent action to save the lives of humanitarians in the besieged part of the city."

It added: "We have good reason to fear for our lives. The regime and its allies have falsely claimed many times that our unarmed and impartial rescue workers in the White Helmets are in fact affiliated with radical extremist groups.

"Our civil defence centres have been targeted and our rescue equipment destroyed. White Helmet volunteers have been purposefully killed in double-tap airstrikes. Hospitals and medical points where doctors and nurses have been working around the clock to save lives have also been targeted repeatedly.

"Countless White Helmets, doctors, nurses and humanitarians have been targeted and killed in the regime's cruel assault on Aleppo.

"It follows then that when the Syrian regime takes over our neighbourhoods, we will be treated as terrorists and the threat of execution or detention is imminent for all White Helmet volunteers and other humanitarian workers."

In pleading for safe passage, the group said the International Committee of the Red Cross, the United Nations and the UN Security Council were responsible for their lives.

The Nobel Peace Prize nominated Syrian Civil Defence claim to have saved some 78,000 lives across the country.

At the end of November, the group said it was unable to continue rescue efforts due to continued bombardment and a shortage of fuel.

Continued regime bombing has also put all of the eastern neighbourhoods' hospitals out of service, as well as having destroyed "more than half" of the White Helmets' equipment.

This is not about who is right, or who is wrong. This is about people. Bleeding, dying, being made orphans, every day

Meanwhile, a doctor working for the Red Cross in Syria has also made a desperate plea for help, describing east Aleppo as "a ghost town of smashed concrete. An end of the world place. Like a fury had swept through".

"This is not about who is right, or who is wrong. Who is winning, who is losing. This is about people: flesh and blood, human beings. Bleeding, dying, being made orphans, every day," he wrote in a letter to the BBC.

"I feel so very sad, today. Please, there have to be some limits to this war."