At least 15 civilians have reportedly been killed by a suspected barrel bomb attack on a funeral being held in the Syrian city of Aleppo.

Residents had gathered in the rebel-controlled Bab al-Nayrab district to mourn 11 children who died in air strikes two days before on Saturday when the explosions struck.

Mohammed Khandakani, a hospital volunteer, said one of the injured victims told him two barrel bombs were dropped within minutes, injuring an ambulance driver responding to the first attack and hampering rescue efforts.

Rescue workers search for victims through the rubble of a building destroyed during a reported barrel bomb attack in a rebel-held neighbourhood in eastern Aleppo on August 27, 2016 (AFP/Getty Images)

Footage posted by activists online showed relatives screaming as victims were carried into a side street in body bags, leaving trails of blood on the floor.

A dead body on an abandoned stretcher could be seen next to a partially crushed ambulance, surrounded by rubble and scattered body parts.

A baby was visible among the bodies of the dead as children covered in dust were pulled from the ruins. The images could not be independently verified.

The Syrian Network group put the death toll from Saturday's attacks at 11 but the pro-rebel Aleppo Media Centre said more than 20 people died.

Helicopters flown by forces loyal to Bashar al-Assad were suspected of carrying out the attack, although officials have persistently denied using barrel bombs.

The cheap munitions see containers packed with explosives and shrapnel before being rolled out of helicopters and have were condemned for inflicting indiscriminate casualties in civilian areas by the UN Security Council.

A girl who survived bombing on the rebel held Bab al-Nayrab neighborhood of Aleppo on 27 August (Reuters)

Bab al-Nayrab is in a rebel-controlled part of Aleppo, which is split between opposition and government control.

At least 13 people died in Thursday’s bombing, which destroyed several houses.

In a hospital, footage showed several toddlers and children being treated for wounds, next to crying family members covered in blood.

Aleppo, Syria’s most populous city before the start of the civil war, has been devastated by four years of bombing by both sides.

Both the Assad regime and its Russian backers are accused of killing civilians with air strikes, while rebels have carried out bomb and rocket attacks on residents living in government districts.

Fierce fighting continues between regime troops and a coalition of Islamist militias led by the former al-Qaeda affiliate Jabhat al-Nusra, who are battling to maintain a corridor between opposition areas and the rest of the Aleppo province after rebels broke the siege of the city earlier this month.

The video which shows the suffering of the children of Aleppo

Pressure for a lasting ceasefire between all parties in Aleppo has increased following air strikes that injured Omran Daqneesh and killed his brother, with images of the Syrian boy sitting dazed and covered in blood provoking horror around the world.

The United States and Russia held talks on Friday aiming to agree a new cessation of hostilities but did not achieve a resolution.

The US is leading a coalition including Britain and more than a dozen other nations that are targeting Isis with air strikes and backing rebels fighting the terrorist group on the ground.

But Russia, alongside Iran and China, is supporting President Assad and follows the Syrian government’s designation of all opposition groups as “terrorists”.

John Kerry, the US Secretary of State, said he and the Russian foreign minister Sergei Lavrov had established a “path forward” after nine hours of discussion in Geneva.

“We don't want to have a deal for the sake of the deal,” Mr Kerry said. “We want to have something done that is effective and that works for the people of Syria, that makes the region more stable and secure, and that brings us to the table here in Geneva to find a political solution.”

In pictures: Aleppo bombing Show all 14 1 /14 In pictures: Aleppo bombing In pictures: Aleppo bombing Bombing in Aleppo Smoke rises after airstrikes on the rebel-held al-Sakhour neighborhood of Aleppo, Syria April 29, 2016. Reuters In pictures: Aleppo bombing Bombing in Aleppo A Syrian family runs for cover amid the rubble of destroyed buildings following a reported air strike on the rebel-held neighbourhood of Al-Qatarji in the northern Syrian city of Aleppo, on April 29, 2016. AFP/Getty Images In pictures: Aleppo bombing Bombing in Aleppo A man reacts as he stands on blood stains at a site hit by airstrikes in the rebel held area of Aleppo's al-Fardous district, Syria, April 29, 2016. Reuters In pictures: Aleppo bombing Bombing in Aleppo The damage of the airstrikes in the rebel-held area of Aleppo on April 28 Reuters In pictures: Aleppo bombing Bombing in Aleppo The damaged the Medecins Sans Frontieres (MSF)-backed al-Quds hospital after it was hit by airstrikes, in a rebel-held area of Syria's Aleppo Reuters In pictures: Aleppo bombing Bombing in Aleppo Syrians evacuate an injured man amid the rubble of destroyed buildings following an air strike on a rebel-held of Aleppo on April 29, 2016. AFP/Getty Images In pictures: Aleppo bombing Bombing in Aleppo People inspect the damage at a site hit by airstrikes, in the rebel-held area of Aleppo's Bustan al-Qasr AP In pictures: Aleppo bombing Bombing in Aleppo A man leads a woman in tears and child out of the scene after airstrikes hit Aleppo AP In pictures: Aleppo bombing Bombing in Aleppo Civil defence members search for survivors after an airstrike at a field hospital in the rebel held area of al-Sukari district of Aleppo Reuters In pictures: Aleppo bombing Bombing in Aleppo A Syrian boy is comforted as he cries next to the body of a relative who died in a reported air strike in the rebel-held neighbourhood of al-Soukour in the northern city of Aleppo Getty Images In pictures: Aleppo bombing Bombing in Aleppo A Syrian family walks amid the rubble of destroyed buildings following a reported air strike in the Bustan al-Qasr rebel-held district of the northern Syrian city of Aleppo Getty Images In pictures: Aleppo bombing Bombing in Aleppo Syrian civil defence volunteers and rescuers remove a baby from under the rubble of a destroyed building following a reported air strike on the rebel-held neighbourhood of al-Kalasa in the northern Syrian city of Aleppo Getty Images In pictures: Aleppo bombing Bombing in Aleppo Syrians help a wounded youth following an air strike on the Fardous rebel held neighbourhood of the northern Syrian city of Aleppo Getty Images In pictures: Aleppo bombing Bombing in Aleppo Syrian civil defence volunteers evacuate people from a damaged building following a reported airstrike in the rebel-held neighbourhood of Tareeq al-Bab in the northern city of Aleppo

The main focus of talks has been over how to separate opposition groups from jihadists as complex alliances continue to shift.

They were held as rebels and civilians were evacuated from the Damascus suburb of Daraya by regime forces, effectively surrendering it to the government after a gruelling four-year siege.

The UN warned that the “world was watching” as thousands of people were transported in buses to other rebel-controlled areas of Syria, while humanitarian groups expressed concern for their safety.

Sireen, a teacher in Daraya, told Save the Children residents had no choice but to leave their homes, adding: “The old people, the children, the young people, everyone has to leave. It’s a done deal.”

Sonia Khush, the charity’s director for Syria, said civilians must be treated with dignity and respect in the evacuation, which was “not an answer” to sieges across Syria.

“There are concerns for the safety and freedom of movement of civilians who are being transferred into shelters in government-held areas,” she added.

A Syrian Arab Red Crescent convoy waits at the entrance of Daraya ahead of the evacuation on 26 August (Reuters)

“Mothers are particularly worried for the fate of their teenage sons as they leave Daraya. Families should be allowed to stay together and children in particular need to be protected.”

Tobias Ellwood, the minister for the Middle East, called on the Assad regime and its supporters to ensure their safe passage and “equally protect those who choose to stay” in accordance with international humanitarian law.

“The citizens of Daraya were among the first to hold peaceful protests for a better Syria,” he added.

“They have been besieged for years, enduring terrible suffering under sustained regime airstrikes and cut off from humanitarian aid. We utterly condemn the appalling violence inflicted by the regime on this town.

“The UN must be granted immediate humanitarian access to Daraya and to all others in need in Syria.”