Russia’s defence ministry says 20 people have been killed and 28 wounded when a Ukrainian missile with a cluster charge exploded in the city of Donetsk in eastern Ukraine.
The ministry provided no evidence and Ukraine denied launching such an attack.
Reuters could not independently verify the statements by either side.
“It is unmistakably a Russian rocket or another munition, there’s not even any point talking about it,” Ukrainian military spokesman Leonid Matyukhin told a televised briefing.
Pro-Russian separatists who control part of Ukraine’s Donetsk region said earlier that a child was among those hit in the alleged strike and they accused Ukraine of committing a war crime.
Ukraine has denied suggestions it would try to recapture the eastern cities of Donetsk and Luhansk, under the control of Russian-backed forces since 2014, by force.
Ukraine and its allies have previously accused Russia of planning “false flag” operations to create pretexts for further military offensives against Ukraine.