World Bulletin / News Desk

Syrian government forces have dropped barrel bombs on Aleppo nearly daily this year, amounting to the war crime of targeting civilians, and insurgent shelling has caused mass casualties, U.N. investigators said on Tuesday.

Both the military and rebel groups, including Islamic State, have imposed sieges to "devastating effect", depriving residents of food and medicine and leading to malnutrition and starvation, they said in their latest report.

"The government's campaign of shelling and aerial bombardment sits alongside the besieging of areas and the arrest and disappearance of predominantly fighting-age males from restive areas at its checkpoints," Paulo Pinheiro, chairman of the U.N. commission of inquiry, told the Human Rights Council.

"Shelling of civilian-inhabited areas by non-state armed groups - including but not limited to ISIL, Jabat al-Nusra and Jaysh Al-Islam - have terrorised men, women and children living in localities held by the government," he said.

More than 220,000 people have been killed in the four-year conflict which 4 million refugees have fled.

This year, government planes and helicopters have bombarded areas of eastern Aleppo province, "mostly barrel bombings - on a nearly daily basis," the independent experts said. Its bombing of towns and cities in Deraa and Idlib had also intensified.

"The continuing use of barrel bombs in aerial campaigns against whole areas, rather than specific targets, is in violation of international humanitarian law and, as previously documented, amounts to the war crime of targeting civilians," the report said.

The investigators, who have drawn up five confidential lists of suspected war criminals on all sides, warned: "The flight paths of helicopters responsible for the dropping of barrel bombs are being documented. Those in command of the bases and airstrips where helicopters are loaded and from where they take off must be held accountable."

Syrian Ambassador Hussam Eddin Aala rejected the inquiry's findings about government practices, adding:

"The terrorist group ISIL has committed massacres in Palmyra and caused deaths and injury of hundreds of people, however these crimes don't seem to have found their way into report."

Aala accused the U.N. investigators of "collusion and bias" for failing to denounce Turkey, Saudi Arabia and Qatarfor supporting rebels fighting to topple President Bashir al-Assad.

U.S. ambassador Keith Harper denounced the Damascus government's use of barrel bombs and imprisonment of "tens of thousands of Syrians, subjecting them to torture, sexual violence, inhumane conditions and denial of fair trials".