An apparent Russian air strike destroyed a paediatric and maternity hospital in the besieged Ukrainian city of Mariupol, triggering global outrage.
Russian troops closed in on the capital Kyiv, as the two countries prepared for their first high-level talks since Russia launched its deadly invasion two weeks ago.
As fighting raged for a 14th day, a Ukrainian official said a Russian air strike on a children's hospital in Mariupol wounded at least 17 staff.
Ukrainian President Volodymyr Zelenskyy on Wednesday (local time) posted a video on Twitter showing massive destruction at the large medical complex, including blown-out windows and internal walls ripped out, which he said was caused by a "direct strike by Russian troops" and left adults and children "under the wreckage".
Mr Zelenskyy condemned the attack as an "atrocity" and called again for a no-fly zone to be imposed over the country. NATO has refused to do this.
Russian foreign ministry spokeswoman Maria Zakharova claimed Ukrainian "nationalist battalions" were using the hospital to set up firing positions after moving out staff and patients.
The White House on Wednesday slammed what it called "barbaric" use of force against civilians, while UK Prime Minister Boris Johnson described the attack as "depraved".
A UN spokesman aid no health facility "should ever be a target".
Russian forces have made rapid advances towards the capital Kyiv, approaching Brovary, a large eastern suburb of the capital, journalists from news agency AFP saw.
"The columns of Russian tanks yesterday took two villages a few kilometres away," said Volodymyr, a 41-year-old resident of Velyka Dymerka, 15 kilometres from Brovary.
"They shoot to scare people and force them to stay at home, steal what they can to get supplies and settle among the inhabitants, so that the Ukrainian forces do not bomb them."
Fighting has intensified in the area, with Ukrainian forces trying to repel the Russian tanks, local residents and volunteers of the Ukrainian forces told AFP.
Ukrainian emergency employees work at the side of a maternity hospital damaged by shelling in Mariupol, Ukraine, Wednesday, on 9 March, 2022. Source: AP / Evgeniy Maloletka/AP
Chernobyl 'fully disconnected'
The invasion has raised nuclear concerns, with Ukraine saying on Wednesday that power has been cut to Chernobyl, site of the world's worst nuclear disaster in 1986, which has been seized by Russian forces.
The defunct plant, housing decommissioned reactors and radioactive waste facilities seized by Russia at the start of the war, "was fully disconnected from the power grid", Ukraine's energy operator Ukrenergo said.
The UN atomic watchdog, the International Atomic Energy Agency (IAEA) said that while the development violated a "key safety pillar", it saw "no critical impact on safety" at Chernobyl.
Russia also attacked and seized Europe's largest atomic power plant, Zaporizhzhia, last week, drawing accusations of "nuclear terror" from Kyiv.
US deploys hardware to Poland
The United States said on Wednesday it was redeploying two anti-aircraft batteries from Germany to Ukraine's neighbour Poland, a Pentagon official said.
Mr Zelenskyy earlier urged Western powers to decide on a Polish offer to supply Ukraine with fighter jets, after the US rejected an initial plan as unviable.
"We ask you again to decide as soon as possible. Send us planes," he said.
Russia's war has sent around 2.2 million refugees across Ukraine's borders in what the UN has called Europe's fastest-growing refugee crisis since World War Two, and sparked fears of wider conflict.
Fears are mounting that Russia will encircle Kyiv, where an orchestra on Wednesday performed in the city's Maidan Square in a morale-boosting concert that included the EU anthem Ode to Joy.
Evacuation truce
Residents cross a destroyed bridge as they flee from the frontline town of Irpin, Kyiv region, Ukraine, on 9 March 2022. Source: EPA, AAP / Mikhail Palinchak
Safe routes were opening out of five Ukrainian areas including suburbs of the capital Kyiv that have been devastated by Russian shelling and air strikes.
Russia had vowed to respect a 12-hour truce starting at 9:00 am (6pm AEDT) to allow civilians to flee six areas that have been heavily hit by fighting, Ukrainian Deputy Prime Minister Iryna Vereshchuk said.
For the first time the corridors included Irpin, Bucha and Gostomel, a cluster of towns on the northwestern outskirts of Kyiv that have been largely occupied by Russian forces.
A corridor was also agreed for the port town of Mariupol, where several previous evacuations have failed, leaving thousands of people without water or power since Friday.
People walk next to an apartment building hit by shelling in Mariupol, Ukraine, on Monday, 7 March, 2022. Source: AP, AAP / Evgeniy Maloletka
On Tuesday at least 10 people were killed in a Russian military attack on homes and other buildings in the eastern Ukrainian town of Severodonestk, a local official for the Luhansk region said in a statement on Telegram.
'Economic war on Russia'
Western allies have hit Russia with unprecedented sanctions, with the US on Tuesday announcing restrictions on the oil imports that help bankroll Moscow's war machine.
The spike in energy prices caused by Russia's war in Ukraine will produce effects comparable to the 1973 oil shock, French Economy Minister Bruno Le Maire warned.
The EU on Wednesday agreed to add more Russian oligarchs to the sanctions blacklist, and to cut three Belarusian banks from the global SWIFT payments system over Minsk's support for the Kremlin's attack.
British Foreign Secretary Liz Truss called on the entire G7 grouping to ban Russia oil imports.
A corporate boycott grew too, with Dutch brewery Heineken and Universal Music joining McDonald's, Coca-Cola and Starbucks among the big brands to suspend business in Russia.
The Kremlin, scrambling to impose measures to limit the economic fallout, hit back by accusing the US of having "declared economic war on Russia".
Russian President Vladimir Putin has vowed the "neutralisation" and "denazification" of pro-Western Ukraine, and raised Russia's nuclear alert.
Russian foreign ministry spokeswoman Maria Zakharova said that "some progress has been made" in three rounds of negotiations with officials from Ukraine, adding that Russian troops were not trying to "overthrow" the Ukrainian government.
No no-fly zone
Western governments have baulked at the Ukranian president's calls for a no-fly zone to defend Ukraine's skies, fearing it would trigger a conflict with nuclear-armed Russia.
"The prospect of fighter jets... departing from a US/NATO base in Germany to fly into airspace that is contested with Russia over Ukraine raises serious concerns for the entire NATO alliance," spokesman John Kirby said.
The West has instead relied on funnelling weapons and aid into Ukraine.
British Defence Minister Ben Wallace said Wednesday his country had delivered 3,615 NLAW anti-tank weapons, and would shortly start shipping a "small consignment" of Javelin anti-tank missiles.
Canada's Prime Minister Justin Trudeau said his country will send an additional $50 million worth of military equipment to help Ukraine.
Talks on Thursday
Russian Foreign Minister Sergei Lavrov and his Ukrainian counterpart Dmytro Kuleba were set to hold face-to-face talks in southern Turkey Thursday (local time) — their first such meeting since the invasion.
Mr Kuleba confirmed in a video on Facebook he was preparing to meet Mr Lavrov on Thursday, warning that his expectations were "limited".
