Damage is seen in the water pumping station in the village of Ain al-Fija
Damage is seen in the water pumping station in the village of Ain al-Fija in the Wadi Barada valley near Damascus, Syria in this handout picture provided by SANA Reuters

The Syrian government of Bashar al-Assad deliberately bombed the water supply in Damascus, cutting off the water supply to 5.5 million civilians in the city and so doing committed a war crime, the UN has said.

The UN's Independent International Inquiry on Syria said Assad's forces carried out the war crimes in December 2016 when they hit the al-Fija spring with at least two air strikes. In the aftermath of the attack the civilians were deprived of access to water for over a month and half.

Reuters reported rebels forces controlled the springs in Wadi Barada valley, north-west of Damascus since 2012 but later faced a major offensive by pro-Assad troops. They with withdrew from the springs at the end of January.

"While the presence of armed group fighters at [the] spring constituted a military target, the extensive damage inflicted to the spring had a devastating impact on more than 5m civilians in both government and opposition controlled areas who were deprived of regular access to potable water for over one month," the commission's report said. "The attack amounts to the war crime of attacking objects indispensable for the survival of the civilian population, and further violated the principle of proportionality in attacks."

However, the commission ruled out the possibility Assad fighters deliberately poisoned the water supply as was reported by rebel groups at the time.

Vehicles bringing people out of eastern Aleppo
Forces loyal to Syria's President Bashar al-Assad sit on a tank as a convoy of buses and other vehicles bringing people out of eastern Aleppo turns back in the direction of the besieged rebel enclave, Syria December 16, 2016. Reuters

The commission, led by Brazilian investigator Paulo Pinheiro reported two weeks ago that the forced evacuation of east Aleppo under siege conditions and constant airstrikes by Syrian and Russian forces was a war

Both warring factions in the final push by pro-Assad forces for control of east Aleppo committed war crimes the UN has said in its report.

It has confirmed what had already been widely reported by human rights groups and international NGOs saying Russian and Syrian forces had carried out indiscriminate attacks on civilian areas, targeting hospitals and other non-military buildings.

The UN also said the Assad regime had repeatedly used chemical weapons and cluster munitions on the civilian population in eastern Aleppo from July until the rebel-held enclave fell on 22 December.