Myanmar’s military has imported at least $1 billion in arms and other material since it staged a coup in February 2021, a UN expert said on Wednesday in a new report that calls out Russia and China for aiding the junta's deadly campaign to crush its opposition. 

Since the military seized power and jailed democratic leaders, some opponents of military rule have taken up arms, in places joining ethnic minority insurgents, and the military has responded with air strikes and heavy weapons, including in civilian areas. 

Russian-made Mi-35 helicopter, MiG-29 fighter jets and Yak-130 light aircraft, and Chinese K-8 jets, have been most frequently used to conduct air strikes that have hit schools, medical facilities, homes and other civilian sites, said the report by Tom Andrews, the UN Special Rapporteur on the human rights situation in Myanmar.

In a single attack on a village gathering organized by the military's opponents in Sagaing region on April 11, two bombs dropped from a Yak-130 killed at least 160 people, reportedly including nearly 40 children, the report said. 

Myanmar’s military says it is targeting insurgents and after the Sagaing attack said any civilians killed were probably supporters of opponents it calls "terrorists." 

“The good news is we now know who is supplying these arms and the jurisdictions in which they operate,” Andrews said in a statement, calling for UN members to “step up and stop the flow of arms” with a complete ban on the arms transfers to Myanmar’s military, enforcement of existing bans and coordinated sanctions.

The UN expert used trade data to detail transfers of arms and other goods, including raw materials for Myanmar’s domestic arms production, to the military since the coup worth $406 million from Russia and $267 million from China, including from state-owned entities in both countries. 

State-owned entities in India also made a smaller volume of transfers, and companies in Singapore, India and Thailand were also involved in transfers to the military. 

Some $227 million of material came from Rosoboronexport, Moscow’s state-owned arms exporter, which has transferred SU-30 fighter jets, supplies for MiG-29 jets and rocket launch systems to Myanmar, the report said. 

Other Russian companies provided a range of tools, equipment and spare parts for Russian-supplied weapons systems, it said. 

“Weaponry provided by Russian suppliers has been used to commit probable war crimes and crimes against humanity in Myanmar,” the report said. 

The UN missions of the five countries mentioned in the report as sources of arms and material did not immediately respond to requests for comment. 

At a news conference in New York, Andrews said Chinese officials had earlier criticized his reporting, saying he was vilifying legitimate trade in arms and operating outside his mandate by conducting analysis. Russian officials had expressed a similar response, Andrews said.