The European Union presidency has called for an international tribunal over Russia's invasion of Ukraine after the discovery of mass graves in the recently liberated Ukrainian town of Izium.
The call, from Czech Foreign Minister Jan Lipavsky, came after Ukrainian officials claimed that more than 440 graves had been found near the city’s cemetery.
Ukrainian President Volodymyr Zelenskyy said they contain the bodies of civilian adults and children, as well as soldiers, showing signs of violent deaths, some possibly from torture.
On Saturday, the Czech Republic, which currently holds the rotating presidency of the EU bloc, condemned attacks against civilians as "abhorrent".
"Russia left behind mass graves of hundreds of shot and tortured people in the Izyum area," Mr Lipavsky wrote on Twitter.
"In the 21st century, such attacks against the civilian population are unthinkable and abhorrent. We must not overlook it. We stand for the punishment of all war criminals."
"I call for the speedy establishment of a special international tribunal that will prosecute the crime of aggression."
Mr Zelenskyy said on Saturday that exhumation work - at the site of the mass burial that had been found - had continued in Izium, in the Kharkiv region in the country's north-east.
"More than ten torture chambers have been found in the liberated areas in the Kharkiv region - in various cities and towns," he said.
"As the occupiers fled, they also left behind the devices for torture. Even at the ordinary railway station in Kozacha Lopan, a room for torture and tools for electric torture were found."
"It's just a railway station. Torture was a widespread practice in the occupied territory. That is what the Nazis did."
In other developments, the UN's nuclear watchdog says one of Ukraine's Zaporizhzhia nuclear power plant's four main power lines has been repaired.
It is now back to supplying the plant with electricity from the Ukrainian grid a fortnight after it went down.
The power at Europe's biggest nuclear power plant sparked major concern after the last main line went down and three back-up lines were disconnected.
The six-reactor plant was captured by Russian forces in March but is operated by Ukrainian engineers. Russia and Ukraine have blamed each other for shelling at the site.
Moscow has been stepping up its targeting of civilian infrastructure over the last week, as it faces setbacks on the front line, according to the UK's Ministry of Defence.
Ukrainian soldiers are pushing on with their counter-offensive in the country's north-east, after successfully re-taking territory from Russia over recent days.
Since the outbreak of war in February, Russia has been accused of committing war crimes in Ukraine, of using chemical weapons and of executing and raping civilians, including children.