Russia was poised Monday to take the strategic city of Mariupol and unleash a massive offensive in eastern Ukraine, as fresh diplomatic efforts with Moscow to broker a peace offered little hope of de-escalation.
With the war grinding toward its seventh week, Austria's leader said he had raised alleged Russian atrocities as he became the first European leader to visit President Vladimir Putin since the invasion began, AFP said.
Ukraine says more than 1,200 bodies have been found in devastated areas around Kyiv, with authorities pursuing "500 suspects" including Putin and other top Russian officials.
Seven bodies were found Monday under the rubble of two multi-storey buildings in Borodianka, in the Kyiv region, the state emergency service said, bringing the total to 19.
French investigators arrived in Ukraine to help probe suspected war crimes, as the European Union earmarked 2.5 million euros ($2.7 million) to the International Criminal Court for future Ukraine cases.
Russia is believed to be trying to connect occupied Crimea and Moscow-backed separatist territories Donetsk and Lugansk in Donbas and has laid siege to Mariupol, once a city of more than 400,000 people.
"Today will probably be the last battle, as the ammunition is running out," the 36th marine brigade of the Ukrainian armed forces said on Facebook.
"It is death for some of us, and captivity for the rest," the brigade added, saying it had been "pushed back" and "surrounded" by Russian troops.
Appealing to South Korea's National Assembly for military assistance, Ukraine's President Volodymyr Zelensky told lawmakers Russia had "completely destroyed" the city and "burned it to ashes".
"At least tens of thousands of Mariupol citizens must have been killed," he said.
Russian forces are turning their focus to the Donbas region in the east, where Zelensky said Russian troops were preparing "even larger operations".
- 'Logic of war' -
Weekend strikes hampered evacuations in and around Kharkiv in the northeast, killing 11 people including a seven-year-old, the regional government said.
Russian missiles nearly obliterated the airport of Dnipro, an industrial city of one million around 200 kilometers (125 miles) to the south, according to local authorities.
Lugansk governor Sergiy Gaiday said a missile strike Friday on a railway station in the eastern city of Kramatorsk that killed 57 people had left many afraid to flee.
"You are alive because a Russian shell has not yet hit your house or basement -- evacuate, buses are waiting, our military routes are as secure as possible," he wrote on Telegram.
Russia has denied carrying out the strike, as well as involvement in any other war crimes.
The US defense department reported a Russian convoy that had been observed heading for Izyum, an hour's drive north of Kramatorsk, saying it appeared to be a mix of personnel-carriers, armored vehicles and possible artillery.
On the diplomatic front, EU foreign ministers met Monday to discuss a sixth round of sanctions, with concerns that divisions over a ban on Russian gas and oil imports could blunt their impact.
Austrian Chancellor Karl Nehammer said his meeting with Putin at the Russian leader's residence outside Moscow was not "a visit of friendship," adding that he "mentioned the serious war crimes in Bucha and other locations".
He added that he was "rather pessimistic" about the chances of diplomacy, describing Putin as having "massively entered into a logic of war".
US President Joe Biden held virtual talks with Indian Prime Minister Narendra Modi, just weeks after saying New Delhi had been "shaky" in its response to the invasion.
"There were conversations about how to mitigate the destabilizing impacts of Putin's war, including on food supply, where India is in a position to assist," a US official said.
- 'Prevent one massacre' -
The EU's top diplomat Josep Borrell said Russia is responsible for the escalating global food crisis because of its bombing of wheat stocks and preventing ships from carrying grain abroad.
And the World Trade Organization cautioned separately that the war could almost halve global trade growth this year.
Despite Kyiv's allegations of Russian atrocities, Ukraine's Foreign Minister Dmytro Kuleba told US news network NBC on Sunday he was still open to negotiating with Moscow.
"If sitting down with the Russians will help me to prevent at least one massacre like in Bucha, or at least another attack like in Kramatorsk, I have to take that opportunity," he said.
Bucha -- where authorities say hundreds were killed, some with their hands bound -- has become emblematic of the brutality allegedly inflicted under Russian occupation.
More than 4.5 million Ukrainian refugees have now fled their country, the United Nations refugee agency said -- 90 percent of them women and children.
At least 183 children have died and 342 were wounded in Ukraine in 46 days of the Russian invasion, the prosecutor general's office said on Telegram.