Russian attacks against civilians in Ukraine, including systematic torture and killing in occupied regions, amount to war crimes and possibly crimes against humanity, according to a report from a U.N.-backed inquiry released Thursday.

The sweeping human rights report, released a year to the day after a Russian airstrike on a theater in Mariupol killed hundreds sheltering inside, marked a highly unusual condemnation of a member of the U.N. Security Council.

Among potential crimes against humanity, the report cited repeated attacks targeting Ukrainian infrastructure since the fall that left hundreds of thousands without heat and electricity during the coldest months, as well as the “systematic and widespread” use of torture across multiple regions under Russian occupation.

A commission of inquiry is the most powerful tool used by the U.N.-backed Human Rights Council to scrutinize abuses and violations around the world. The investigation released Thursday was set up during an urgent debate shortly after Russia’s invasion last year.

The commission’s three members are independent human rights experts, and its staff gets support and funding from the council and the U.N. human rights office.

The report’s authors noted a “small number” of apparent violations by Ukrainian forces, including one they said was under criminal investigation by Ukrainian authorities, but reserved the vast majority of their report for allegations against Russia.

Russia did not respond to the inquiry’s appeals for information.

Most of the abuses highlighted by the investigation were already well known, but the findings come with the imprimatur of the international community: The experts work under a mandate overwhelmingly created last year by the Human Rights Council, which brings together the governments of 47 U.N. member countries.

Ultimately, the report may add to efforts to boost accountability for crimes committed in the war — whether by the International Criminal Court or by some individual countries that have taken on the right to apply “universal jurisdiction” to prosecute atrocities, wherever they may take place.