War crimes prosecutors visiting the site of civilian killings called Ukraine a "crime scene" Wednesday, as tens of thousands of Ukrainians fled their country in advance of a fresh assault to the east.
The visit by the International Criminal Court's chief prosecutor to Bucha -- the Kyiv suburb now synonymous with scores of atrocities against civilians discovered in areas abandoned by Russian forces -- came as the new front of the war shifts eastward, with new allegations of crimes inflicted on locals.
"Ukraine is a crime scene," the ICC's chief prosecutor, Karim Khan, told reporters in Bucha. The Hague-based court investigates and prosecutes war crimes, crimes against humanity, and genocide.
"We're here because we have reasonable grounds to believe that crimes within the jurisdiction of the court are being committed," said Khan, promising to "follow the evidence" as forensic teams began their work.
To the south, Ukrainian forces struggled to hold the key strategic port of Mariupol Wednesday as artillery pounded the battered and besieged city that has been cut off from the rest of the country since early March and where Ukrainian President Volodymyr Zelensky has estimated "tens of thousands" of civilian deaths.
Russia's defence ministry said Wednesday that 1,026 Ukrainian soldiers from the 36th Marine Brigade had surrendered in Mariupol, including 162 officers. Ukraine has not confirmed the claim.
Following its pullback earlier this month from areas north of Ukraine's capital, Kyiv, Russia is refocusing its efforts eastward, the new frontline of the nearly seven-week war.
It appears aimed at capturing more territory in Donbas, where Russian-backed separatists control the Donetsk and Lugansk regions, to create a solid southern corridor -- including the port of Mariupol -- to occupied Crimea.
- Permeated with pain -
As Zelensky warned "the whole of Eastern Europe" was at risk if Europe wasted time in stopping Moscow, the Polish and Baltic presidents visited Ukraine in a show of support, while Britain said it had slapped sanctions on Russian separatists in Eastern Ukraine and additional oligarchs.
"It is hard to believe that such war atrocities could be perpetrated in 21st-century Europe, but that is the reality," said Lithuanian President Gitanas Nauseda during a visit to the town of Borodyanka outside Kyiv, calling the area "permeated with pain and suffering".
"Civilian Ukrainians were murdered and tortured here, and residential homes and other civilian infrastructure were bombed."
Britain said it would sanction 178 Russian separatists, including the two "self-styled" leaders of the Russia-backed Donetsk and Luhansk People's Republics, and six more oligarchs and their families.
Meanwhile, the Organization for Security and Co-operation in Europe (OSCE) said Russia had engaged in "clear patterns of international humanitarian law violations" in Ukraine.
The report by the world's largest security body covered the period from Russia's February 24 invasion through April 1, before the discovery of hundreds of bodies in Bucha and elsewhere.
Those images spurred US President Joe Biden on Tuesday to level Washington's strongest accusation yet, of genocide, against Putin's actions in Ukraine, after having previously called the Russian president a "war criminal".
"Putin is just trying to wipe out the idea of even being able to be a Ukrainian," Biden said, defending his statement.
Kremlin spokesman Dmitry Peskov called Biden's accusation "unacceptable" Wednesday, a day after Putin said Russia's military campaign in Ukraine was going to plan while brushing off images of civilian deaths as "fakes".
- 'Hiding crimes' -
In a desperate attempt to flee what Ukrainian authorities warn will be a bloody new clash in the east, more than 40,000 people fled the country in the past 24 hours, the United Nations said Wednesday, bringing to 4.6 million the number of people who have fled since the conflict began.
But Kyiv halted humanitarian corridors in several parts of the country Wednesday, deeming them "too dangerous" for evacuations.
Deputy Prime Minister Iryna Vereshchuk said Russian forces around Zaporizhzhia in the south were blocking buses transporting the evacuated, while shooting at fleeing civilians in Lugansk.
Underscoring the risk to civilians, Ukrainian prosecutors on Wednesday accused Russian troops of shooting six men and one woman the day before in a residential home in the occupied southern village of Pravdyne.
"After this, intending to hide their crime, the occupiers blew up the building with the bodies," prosecutors said in a statement.
Meanwhile, seven civilians were killed by Russian shelling in the northeastern Kharkiv region in the past 24 hours, regional governor Oleg Synegubov said on social media.
- Clean them out -
In Mariupol, air strikes continued, particularly on the port and the huge Azovstal iron and steel works, the Ukrainian army said on Telegram.
The steel plant's maze-like complex has been a focus of resistance in Mariupol, with fighters using a tunnel system below the vast industrial site to slow Russian forces down.
"It's a city within a city," said Eduard Basurin, a representative for pro-Russian separatists in Donetsk, citing subterranean areas that cannot be bombed from above.
"You have to go underground to clean them out, and that will take time."
US Secretary of State Antony Blinken said he could not confirm allegations that Russia had used chemical weapons in the area, but Washington had "credible information" Russia might use tear gas mixed with chemical agents in the besieged port.
- Russians in morgue -
Suggesting a Russian buildup to the east, US private satellite firm Maxar Technologies published images Wednesday it said showed Russian ground forces moving towards the border with Ukraine.
Other convoys in and near the Donbas region comprised around 200 vehicles including tanks, artillery and armoured personnel carriers, it said.
Even as the military focus shifted eastward, the grim work of accounting for the civilian dead continued in areas recently abandoned by Russia's army.
North of Bucha in the town of Gostomel, locals exhumed the body of Mayor Yuriy Prylypko, who authorities said was shot while "handing out bread to the hungry and medicine to the sick" and hastily buried by a local priest.
Up to 400 people are unaccounted for Gostomel, said regional prosecutor Andiy Tkach. AFP witnessed dozens of body bags filling a refrigerated lorry trailer, as two others awaited more corpses.
"Our citizens are murdered and we must bury every person in the right way," said Igor Karpishen, loading the truck.
"I don't have any words to express these feelings."
Zelensky accused Russian forces in occupied towns of committing hundreds of rapes, including of young children and a baby.
Bucha Mayor Anatoly Fedoruk said more than 400 people were found dead after Moscow's forces withdrew, with 25 reported rapes.
Meanwhile, an official in the central Ukrainian city of Dnipro said Wednesday the remains of more than 1,500 Russian soldiers were being kept in its morgues.