Moscow has charged 92 members of the Ukrainian armed forces with crimes against humanity and proposed an international tribunal backed by countries including Bolivia, Iran and Syria, the head of Russia's investigative committee said.

The government's Rossiiskaya Gazeta on Monday quoted committee head Alexander Bastrykin as accusing "more than 220 persons, including representatives of the high command of the Armed Forces of Ukraine, as well as commanders of military units that shelled the civilian population."

The Ukrainians were involved in "crimes against the peace and security of humanity, which have no statute of limitations," he said. Bastrykin, whose committee probes major crimes, said 92 commanders and their subordinates had been charged, and 96 people, including 51 armed forces commanders, declared wanted.

Reuters could not independently verify the committee's allegations. Ukrainian authorities were not immediately available for comment.

The United States and more than 40 other countries agreed earlier this month to coordinate investigations into suspected war crimes in Ukraine.

Since launching what it calls a special military operation in February, Russian forces have bombed Ukrainian cities to ruins and left behind bodies in the streets of towns and villages they occupied. Ukraine says tens of thousands of civilians have died. Moscow denies responsibility.

There have also been some reports of Ukrainians mistreating Russian prisoners, though the vast majority of accusations documented by bodies such as the United Nations are of alleged atrocities committed by Russian invaders and their proxies.

Bastrykin was asked about his committee's investigations into Ukrainian security forces' actions in the self-declared people's republics of Donetsk and Luhansk, separatist, Moscow-backed territories in Ukraine's industrialized east, and whether investigations could take place under U.N. auspices.

Given that the "collective West" openly backed Ukraine, he said it would be more appropriate to work with Russian partners in the Commonwealth of Independent States, the Collective Security Treaty Organization, the BRICS group and the Shanghai Cooperation Organization.

It was "expedient" to involve countries with an independent position on Ukraine, "in particular, Syria, Iran and Bolivia," he added.

Bastrykin said 1,300 criminal investigations had been initiated into members of Ukraine's military, political leadership, radical nationalist associations, and armed formations, with more than 400 people so far held accountable.

Targets of the investigation included Ukrainian Health Ministry employees who he accused, without providing evidence, of developing weapons of mass destruction, as well as citizens of Britain, the United States, Canada, the Netherlands and Georgia.

Eight criminal cases had also been launched into attacks on Russian embassies or other representations in the Netherlands, Ireland, Lithuania, the Czech Republic, Poland, Romania and France, he said.