GENEVA: Syrian activists say they have given U.N. investigators evidence of alleged war crimes committed by Russia and Iranian-backed militia in the battle for the Syrian city of Aleppo, calling for them to face justice for killing civilians and other atrocities.

The United Nations Commission of Inquiry on Syria, which began collecting testimony and evidence five years ago for future prosecutions, has already shared some confidential files with national authorities pursuing foreign fighters.

Fadel Abdel-Ghany, head of the Syrian Network for Human Rights, and Husam al-Katlaby, director of the Violations Documentation Center, met U.N. investigators Wednesday to press the case for probing crimes committed during the long siege and recapture of rebel-held eastern Aleppo last month. Syria, and its ally Russia, have dismissed accusations of abuses or war crimes.

Abdel-Ghany said activists “found a similarity between the violations committed by the Russians and the regime, and sometimes the Russians exceed the regime in some kinds of violations.” “We recorded the killing of 1,305 civilians at the hands of Russian forces,” he told Reuters, referring to victims of hundreds of Russian airstrikes between July and December 2016. Roughly one-third of fatalities were children.

After months of bombardment and a final few weeks of intense airstrikes and Syrian army advances on the besieged part of Aleppo, a local cease-fire was reached on Dec. 15 which allowed tens of thousands of civilians and fighters to leave.

“The Russian air force was trying to target specific points, for example hospitals, schools or whatever. They fly at higher altitude [than the Syrian air force] – this comes through in the testimonies, the interviews,” Katlaby said.

Since the Russian air campaign began on Sept. 30, 2015, Russian forces have killed “a minimum” of 4,000 Syrians in all, Abdel-Ghany said. “We have all documented, by name, details, date, photos.”

The activists, joined by the “White Helmets” civil defense teams and the Independent Doctors Association, documented 31 cluster munitions attacks in Aleppo by Russian forces and three by Syrian government forces, as well as their use of banned incendiary weapons, Abdel-Ghany said. “There is clear evidence that the attacks by Russia on Syrian civilians constitute war crimes,” the four groups said in a joint letter to the COI’s chairman Paulo Pinheiro, whose team is expected to issue a report on Aleppo in February.

“We also urge the Commission to explore fully all credible accounts of Iran’s complicity in war crimes in Aleppo,” it said, citing the “central role” of Iranian-backed militias in enforcing the siege and preventing civilians from fleeing.

Iran, which has backed President Bashar Assad with weapons, oil shipments and military advisers, denies any involvement in the killing of civilians and emphasizes Tehran’s determination to support Assad in his “fight against terrorism.”

Abdel-Ghany said a special tribunal should be set up to try war crimes, since Russia would veto attempts to send the issue to the International Criminal Court.