Charity group Save the Children has revealed a litany of atrocities against children in Syria and urged the UN to tackle them immediately.

The report, entitled 'Untold Atrocities, The Story of Syria's Children', is based on personal accounts, and reveals that many children in Syria have faced torture, imprisonment and adbuction during the country's 18-month civil war.

A teenager named Khalid told the charity: "They hung me up from the ceiling by my wrists, with my feet off the ground. Then I was beaten." Showing scars, he said his tormentors frequently used to stub out their cigarettes on him.

Nearly all the children featured in the report have witnessed the death of at least one family member - an experience which is widely believed to create severe and lasting trauma.

Some children were even given electric shocks while tormenters made them watch the dying moments of other children.

"The stuff I've heard from children is absolutely appalling. I've heard of children as young as 10 being tortured. I've heard of children, as young as eight, helping to remove dead bodies from rubble, with their own hands," said Save the Children's spokesperson Cat Carter.

The report echoes previous studies carried out by rights groups and the UN, which highlighted a string of atrocities perpetrated by both the Bashar al-Assad regime and the fighting opposition groups during the civil war.

According to activists, more than 30,000 people have lost their lives so far in the bloody uprising since March 2011.

The Save the Children study also coincides with the start of the UN General Assembly's annual meeting, ahead of which Lakhdar Brahimi, UN and Arab League special envoy to Syria, said the situation in the country is extremely bad and getting worse.

"There is no disagreement anywhere that the situation in Syria is extremely bad and getting worse, that it is a threat to the region and a threat to peace and security in the world" said Brahimi, who ruled out an overnight solution for ending the conflict but expressed hope of an eventual resolution.

The veteran Algerian diplomat, who has visited Syrian refugee camps in neighbouring countries, once again stressed the need for a complete change in the political atmosphere of the country.

"I refuse to believe that reasonable people do not see that you cannot go backward, that you cannot go back to the Syria of the past. I told everybody in Damascus and everywhere that reform is not enough anymore, what is needed is change," Brahimi said, hinting at a political transition.