US-led coalition and Russian air strikes caused mass civilian deaths that may amount to war crimes, say UN investigators in the latest report covering the last six months through to January 15.

In this July 26, 2017 file photo, black smoke rises from a coalition air strike which allegedly attacked a Daesh militant position on the front lines on the eastern side of Raqqa, Syria.
In this July 26, 2017 file photo, black smoke rises from a coalition air strike which allegedly attacked a Daesh militant position on the front lines on the eastern side of Raqqa, Syria. (AP)

Air strikes by a US-led coalition and Russia killed civilians in Syria on a large scale last year, while the Assad regime carried out unlawful chemical weapon attacks in rebel-held eastern Ghouta, UN war crimes investigators said on Tuesday.

Daesh militants and other fighting groups committed war crimes including deadly attacks on civilians and using them as human shields, the investigators said in their latest report covering six months through January 15.

During the period, "victims of the Syrian conflict have suffered greatly as violence countrywide re-escalated to new heights," the UN Commission of Inquiry said.

"Syrian regime forces continued to use chemical weapons against armed group fighters in eastern Ghouta," it said in its report.

TRT World 's Sara Firth reports the latest from the Lebanon-Syria border.

Attacks on de-escalation zones

Among other key findings, it said that an air strike by a "Russian fixed-wing aircraft" using unguided weapons last November hit a market, killing at least 84 people in Atareb, west of Aleppo, in a "de-escalation zone" declared by Russia, Iran and Turkey.

It found no evidence that the Russian strike had deliberately targeted the market, but said "this attack may amount to the war crime of launching indiscriminate attacks, resulting in death and injury to civilians," the first time it had explicitly implicated Moscow in possible war crimes.

US air strikes on a school

And three US-led coalition strikes on a school near Raqqa in March 2017, killed 150 residents – roughly five times the toll acknowledged by the Pentagon, which said at the time that dozens of militants and not civilians were killed.

The UN investigators found no evidence that Daesh fighters were at the site, and said the US-led coalition had violated international law by failing in its duty to protect civilians.

The independent investigators called on all sides to allow access to besieged areas and all detainees.

Justice must be served in any peace deal to end the conflict soon which is entering its eighth year, they said.

The report is based on 500 confidential interviews conducted with victims and witnesses abroad or in Syria via social media. The Assad regime has never let the team into the country.

"Vital civilian infrastructure has been decimated by repeated attacks on medical facilities, schools and markets. Humanitarian aid has been instrumentalised as a weapon of war with siege warfare and denial of life-giving assistance used to compel civilian communities and parties to the conflict alike to surrender or starve," it said.

Syrian regime forces used chemical weapons against opposition groups in eastern Ghouta, including chlorine three times in July, and in Harasta on the western edge of the zone in November, the report said.

"The use of chemical weapons is prohibited under customary international humanitarian law regardless of the presence of a valid military target, including when used against enemy fighters," it said.

The Syrian regime has denied using chemical weapons, saying it surrendered its stockpiles after signing the global ban in 2013.

'No pardons or amnesties'

The multi-sided Syrian civil war has killed hundreds of thousands of people and driven at least 11 million from their homes.

Neighbouring countries and global powers have entered the conflict, backing allied forces on the ground.

The United States joined the war in 2014, leading an international coalition carrying out air strikes against Daesh militants in both Syria and Iraq, who were largely defeated last year.

Russia joined the conflict in 2015, providing air and ground support for its allies in the Syrian regime.

The UN investigators, noting that efforts for the UN Security Council to refer Syria to the International Criminal Court (ICC) have stalled, due to Russian vetoes, welcomed national jurisdictions taking up more cases.

Victims must be helped to obtain justice, which should be a "central component" of any negotiated settlement ending the war, they said.

There must be "no pardons or amnesties for those responsible for ordering or carrying out gross human rights violations and committing international crimes such as war crimes, crimes against humanity or genocide."

Re-examining a US-led coalition air strike on a school sheltering displaced people in Al Badiya, Raqqa in March 2017, when the area was controlled by Daesh militants, they found after extensive interviews with survivors and rescuers that "of more than 200 residents in the school, 150 were killed".

"Information gathered by the Commission does not support the claim that 30 Daesh militants were in the school at the time of the strike, nor that the school was otherwise being used by Daesh," it said.

"The international coalition should have known the nature of the target and failed to take all feasible precautions to avoid or minimise incidental loss of civilian life, injury to civilians and damage to civilian objects, in violation of international humanitarian law."

Source: TRTWorld and agencies