A shocked Syrian boy pictured sitting in an ambulance covered in blood and dust after an air strike has become a symbol of civilian suffering in Aleppo, drawing worldwide attention.

As international concern mounted, President Bashar al-Assad's key ally Russia said it was ready to halt fire in the battleground northern city for 48-hour "humanitarian pauses" from next week.

The announcement Thursday followed pleas from the United Nations and the European Union for a halt in the fighting in divided Aleppo to allow aid deliveries.

But it was the haunting image of five-year-old Omran sitting dazed and bloodied in an ambulance that reverberated around the globe, much like the photo of little Aylan Kurdi whose body washed ashore on a Turkish beach last year.

Omran was pulled from the rubble after an air raid on Wednesday in the rebel-held district of Qaterji in the southeast of Aleppo, which has been devastated by the five-year war.

The Aleppo doctor who treated Omran's head wound said in an interview that the boy had been reunited with his parents and that his family were all believed to have survived the strike.

"Omran was afraid and astonished and he didn't cry because he was shocked," the surgeon named by the BBC as Dr. Mohammad said, adding that the child hadn't spoken a word.

"Omran had a lucky chance to spread his story over all the media but every day we have many children who have worse injury and sad stories. They maybe lost their lives or limbs, or many of them became paralysed," he said.

The US State Department called Omran "the real face" of the Syrian conflict.

"That little boy has never had a day in his life where there hasn't been war, death, destruction, poverty in his own country," State Department spokesman John Kirby said at a press briefing.

Photographer Mahmoud Rslan captured the image of Omran, who was plopped onto a seat in an ambulance after being carried out of his family's destroyed apartment by a rescuer.

He has a head full of hair that falls into his eyes and is wearing a T-shirt and shorts, but with bare feet that barely reach the edge of the chair.

"I've taken a lot of pictures of children killed or wounded in the strikes that rain down daily," Rslan told AFP by telephone.

"Usually they are either unconscious or crying. But Omran was there, speechless, staring blankly, as if he did not quite understand what had happened to him."

Aleppo stalemate

Opposition-held neighbourhoods in Aleppo are frequently targeted by air strikes including barrel bombs dropped by regime helicopters.

Syrian and Russian aircraft have been carrying out intense air strikes this week on opposition strongholds across northern Syria to prevent rebels sending reinforcements to the city, a monitoring group said.

Regime aircraft continued to pound rebel positions across Idlib province on Thursday as well as parts of Aleppo province, it said.

Aleppo has been the scene of intense fighting since July 31, when the "Army of Conquest" alliance of rebels and jihadists launched a major offensive to break a regime siege of opposition-controlled districts.

But neither side has achieved a decisive victory despite hundreds dead on both sides.

In Geneva, UN envoy Staffan de Mistura cut short the weekly meeting of the humanitarian taskforce headed by the United States and Russia, in protest at the failure of warring parties to allow aid to reach civilians.

"Not one single convoy in one month has reached any of the humanitarian besieged areas," he told reporters.

Russian defence ministry spokesman Igor Konashenkov later announced that Moscow was "ready to implement the first 48-hour 'humanitarian pause' to deliver humanitarian aid to Aleppo residents" next week.

De Mistura welcomed the move and said the UN was counting on Moscow's help to ensure "the adherence of the Syrian armed forces to the pause, once it comes into effect".

The Syrian conflict has left more than 290,000 people dead and displaced millions since it began in 2011 with the brutal repression of anti-government demonstrations.

Amnesty International said Thursday that Syrian authorities were committing torture on a "massive scale" in government prisons including beatings, electric shocks, rape and psychological abuse that amount to crimes against humanity.

More than 17,700 people are estimated to have died in custody since the conflict began, an average of more than 300 each month, the watchdog said in a report.