UN investigators said Friday that war crimes have been committed in the Ukraine conflict, listing Russian bombings of civilian areas, numerous executions, torture and horrific sexual violence.

Speaking before the UN Human Rights Council, the head of a high-level investigative team listed a long line of serious violations committed since Russia launched its full-scale invasion of Ukraine seven months ago.

Erik Mose, the head of the Commission of Inquiry (COI) set up by the council in March, said the team had seen evidence of numerous executions, many people with their hands tied, and the rape and torture of children.

"Based on the evidence gathered by the Commission, it has concluded that war crimes have been committed in Ukraine," he said.

The categorical nature of the COI statement was unusual, as UN investigators typically refer the final confirmation of war crimes and similar violations to courts of law.

But the team of three independent experts, who were presenting their first verbal update to the council, said the evidence of widespread violations was clear.

Ukraine hailed the findings, with its foreign ministry ambassador-at-large Anton Korynevych telling the council via video link that it marked "an important milestone on a path to accountability for Russia's crimes against the people of Ukraine".

Russia's representative was absent from the room and did not respond to the report, although some countries did come to its defence, including Belarus, Syria and Venezuela.

- Executions, torture -

Mose said the team had been especially "struck by the large number of executions", and the frequent "visible signs of executions on bodies, such as hands tied behind backs, gunshot wounds to the head, and slit throats".

Mose said the commission was investigating such deaths in 16 towns and settlements, and was seeking to document credible allegations regarding many more cases.

The investigators, who have so far only had time to probe abuses in the Kyiv, Chernigiv, Kharkiv and Sumy regions, did not immediately address the latest discovery of mass graves in Izyum, after it and other towns in the east were recaptured by Ukrainian forces this month.

But numerous countries who took the floor after their presentation did.

"As we celebrate Ukraine's liberation of settlements in eastern Ukraine, we cannot help but fear what further Russian atrocities will be uncovered," British ambassador Simon Manley told the council.

Mose said the team planned to expand its investigation, but that it had already received "consistent accounts of ill-treatment and torture", carried out during unlawful confinement.

"Interlocutors described beatings, electric shocks, and forced nudity, as well as other types of violations in such detention facilities," Mose said.

He also decried the forced transfer of detainees to Russia, where some had subsequently "disappeared".

The commission chief said the investigators had also "processed two incidents of ill-treatment against Russian Federation soldiers by Ukrainian forces".

- Sexual violence -

Mose also said the team had documented sexual and gender-based violence, with victims aged between four and 82.

In some cases, the investigators had established that Russian soldiers were the perpetrators, Mose told the council, adding "there are examples of cases where relatives were forced to witness the crimes".

The commission had documented a wide range of crimes against children, he said, including some who were "raped, tortured, and unlawfully confined".

More broadly, the team pointed to Russia's "use of explosive weapons with wide area effects in populated areas", which have killed countless civilians in the conflict.

Looking forward, Mose said the team would broaden its investigation to look at so-called "filtration camps, alleged forced transfer of people" and allegations that Ukrainian children are being taken to Russia for adoption there.

US ambassador Michele Taylor stressed the urgency of probing these issues, pointing to sources saying Moscow had "forcibly deported between 900,000 and 1.6 million Ukrainian citizens".