Ukrainian authorities say Russian troops have captured Europe's biggest nuclear power plant after heavy fighting nearby which set fire to one of its buildings.
The regional military administration released a statement saying that a fire caused by Russian attacks at the Zaporizhzhia plant in Enerhodar caused some damage to the compartment of the plant's number 1 reactor but did not affect its safety.
It said the plant continued to run safely after its capture.
Russia has already captured the defunct Chernobyl plant, about 100 kilometres north of Kyiv.
The assault at Zaporizhzhia had renewed fears that Russia's invasion could result in damage to one of Ukraine's 15 nuclear reactors and trigger another emergency like the 1986 Chernobyl disaster.
Earlier, in an emotional speech in the middle of the night, Ukrainian President Volodymyr Zelenskyy said he had feared an explosion that would be "the end for everyone. The end for Europe. The evacuation of Europe".
"Only urgent action by Europe can stop the Russian troops," he said.
"Do not allow the death of Europe from a catastrophe at a nuclear power station."
Developments on the ground in Ukraine include:
- Russian forces fire on nuclear power plant in Enerhodar
- Heavy fighting for port city Mariupol continues
- At least 33 dead after residential buildings in Chernihiv destroyed
- Vladimir Putin vows to fight "until the end" at peace talks
- Kherson becomes the first major city to be captured
- The Russian assault on Kyiv is faltering
- Much of Ukraine's second city Kharkiv in ruins
- Hundreds of civilians killed as fighting continues elsewhere
While the huge Russian armoured column threatening Kyiv appeared bogged down outside the capital, Russian President Vladimir Putin's forces have brought their superior firepower to bear over the past few days.
They have launched hundreds of missiles and artillery attacks on cities and other sites around the country and made significant gains in the south.
Overall, the outnumbered, outgunned Ukrainians have put up stiff resistance, staving off the swift victory that Russia appeared to have expected.
Russian negotiator Vladimir Medinsky said another round of peace talks had made "substantial progress," but Russian invasion forces continued to surround and bombard Ukrainian cities as the conflict entered its second week.
The fighting has sent more than 1 million people fleeing Ukraine, according to the United Nations.
Russian forces 'shelled nuclear plant'
The fire at the building near Zaporizhzhia nuclear power plant was caused by an attack by Russian troops, Ukrainian authorities reported.
Most experts saw nothing to indicate an impending disaster, but the assault prompted renewed calls for an immediate ceasefire.
"We demand that they stop the heavy weapons fire," Andriy Tuz, a spokesman for the plant in Enerhodar, said in a video posted on Telegram after the attack.
Ukraine's Foreign Minister Dmytro Kuleba called for an immediate ceasefire, warning that if the plant exploded, it would be "10 times larger than Chernobyl".
US Energy Secretary Jennifer Granholm said there was no indication of elevated radiation levels at the Zaporizhzhia plant, which has six reactors and provides more than a fifth of Ukraine's electricity.
The International Atomic Energy Agency said Ukrainian authorities reported that the fire had not affected "essential" equipment.
The plant was later captured by Russian troops.
The American Nuclear Society backed up reports from a White House official saying that the latest radiation levels remained within natural background levels.
"The real threat to Ukrainian lives continues to be the violent invasion and bombing of their country," the group said in a statement.
The plant's reactor is a different type than the one used at Chernobyl, and there should be little risk if the containment vessel is not damaged and outside power can be restored, said Jon B Wolfsthal, a former special adviser to US President Joe Biden when he was US vice-president.
Mr Zelenskyy held separate emergency calls with the leaders of the United States and Britain as fire blazed for several hours while firefighters came under attack.
After his call with Mr Zelenskyy, UK Prime Minister Boris Johnson's office said in a statement that: "The reckless actions of President Putin could now directly threaten the safety of all of Europe."
Mr Johnson said the UK would do everything it could to ensure the situation did not deteriorate further and would be seeking an emergency UN Security Council meeting in the coming hours.
Enerhodar's mayor said Ukrainian forces were battling Russian troops on the city's outskirts.
Video showed flames and clouds of black smoke rising above the city of over 50,000, with people streaming away from the inferno past wrecked cars.
UN nuclear watchdog chief Rafael Grossi called on Russian and Ukrainian troops not to fight in the area of the Zaporizhzhia plant.
"Director-general Grossi appealed for an immediate halt to the use of force at Enerhodar and called on the military forces operating there to refrain from violence near the nuclear power plant," the International Atomic Energy Agency said in a statement.
Fight for port city of Mariupol continues
Heavy fighting continued on the outskirts of the strategic port of Mariupol, on the Azov Sea, plunging it into darkness, knocking out most phone service and raising the prospect of food and water shortages.
"Mariupol remains under Ukrainian control but has likely been encircled by Russian forces," Britain's Ministry of Defence said on Friday.
"The city's civilian infrastructure has been subjected to intense Russian strikes."
Without phone connections, medics did not know where to take the wounded.
Cutting off Ukraine's access to the Black and Azov seas would deal a crippling blow to its economy and allow Russia to build a land corridor to Crimea, seized by Moscow in 2014.
Two cargo ships came under apparent attack at Ukrainian ports.
Six crew members were rescued at sea after an Estonian-owned ship exploded and sank off Odesa, and at least one crew member was killed in a blast on a Bangladeshi ship at Olvia.
Dozens of civilians killed in Chernihiv
Ukraine's state emergencies agency said at least 47 civilians were killed and another 18 wounded in a Russian strike on a residential area in Chernihiv, a city of 280,000 in Ukraine's north.
Video taken in the aftermath of shelling shows firefighters standing in rubble dousing flames with hoses as rescue crews carried at least one person on a stretcher and another helper assisted a person down a ladder.
Smoke spewed from a high-rise building just behind what appeared to be a children's swing set, according to video released by the Ukrainian government.
The agency said Thursday night (local time) that it was forced to suspend the search for more casualties in the rubble because of new shelling.
Earlier, the agency had said at least 33 civilians had been killed and had warned that the death toll could rise.
Peace talks tentatively agree on safe corridors
The second round of talks between Ukrainian and Russian delegations was held in neighbouring Belarus.
But the two sides had little common ground going into the meeting and Mr Putin warned Ukraine that it must quickly accept the Kremlin's demand for its "demilitarisation" and declare itself neutral, renouncing its bid to join NATO.
After the latest talks ended, both delegations said that they had tentatively agreed to allow ceasefires in areas designated safe corridors and that the two sides would seek to work out the details quickly.
"That is, not everywhere, but only in those places where the humanitarian corridors themselves will be located, it will be possible to cease fire for the duration of the evacuation," Ukrainian presidential adviser Mykhailo Podolyak said.
They had also reached an understanding on the delivery of medicines and food to the places where the fiercest fighting was taking place.
Mr Putin told French President Emmanuel Macron he was determined to press on with his attack "until the end," according to Mr Macron's office.
Mr Podolyak said a third round of talks would also be held early next week.
Kherson has fallen
The Russians announced the capture of the southern city of Kherson, a vital Black Sea port with a population of 280,000.
Local Ukrainian officials confirmed the takeover of the government headquarters there, making it the first major city to fall since the invasion began a week ago.
The search for more victims in the rubble was suspended because of renewed shelling.
From Kherson, Russian troops appeared to roll toward Mykolaiv, another major Black Sea port and shipbuilding centre to the west. The regional governor, Vitaliy Kim, said big convoys of Russian troops were advancing on the city.
Assault on Kyiv stalled
Western military analysts believe that a Russian battle plan that aimed for a swift advance and capture of the Ukrainian capital Kyiv has faltered, forcing commanders to change tactics.
The main assault force — a huge convoy of tanks, artillery and logistics support — has been halted for days on a highway north of Kyiv.
A US official said Russian troops were still 25 kilometres out of Kyiv city centre and had made no real progress in days.
The convoy, which earlier in the week had seemed poised to launch an assault on the capital, has been plagued with fuel and food shortages, the official said.
Ukrainian officials said their missile-defence systems have parried numerous attacks, though some missiles have clearly made it through.
Kyiv Mayor Vitali Klitschko said explosions heard overnight in the capital were Russian missiles being shot down.
Military analysts say Russia's columns are now confined to roads as spring thaw turns Ukrainian ground to mud.
Each day the main attack force lies stuck its condition deteriorates, said Michael Kofman, an expert on the Russian military at the Wilson Center in Washington DC.
In Borodyanka, a town 60 km north-west of Kyiv where local people repelled a Russian assault, burnt-out hulks of destroyed Russian armour were scattered on a highway, surrounded by buildings blasted into ruins.
"They started shooting from their APC towards the park in front of the post office," a man said in the apartment where he was sheltering with his family, referring to a Russian armoured personnel carrier.
Kharkiv and surrounds
Swathes of Kharkiv, Ukraine's second city with 1.5 million people, have been blasted into rubble.
There have been mass evacuations of the city.
Residents desperate to escape falling shells and bombs crowded the railroad station and squeezed onto trains, not always knowing where they were headed.
US officials say Russian troops are just outside of the city, but the southern Dnipro River port city's fate remained unclear.
Military strikes on the village of Yakovlivka near Kharkiv destroyed 30 homes, leaving three people dead and seven wounded, according to emergency authorities.
Fighting and evacuations elsewhere
Ukrainian authorities called on the people to defend their homeland by cutting down trees, erecting barricades in the cities and attacking enemy columns from the rear.
In recent days, authorities have issued weapons to civilians and taught them how to make Molotov cocktails.
Families with children fled via muddy and snowy roads in the eastern region of Donetsk.
At least 227 civilians have been killed and 525 wounded, according to the office of the UN High Commissioner for Human Rights, though it acknowledged that is a vast under-count, and Ukraine said more than 2,000 civilians have died.
Russia reported its military casualties Wednesday for the first time in the war, saying nearly 500 of its troops have been killed and almost 1,600 wounded.
An an assessment by the Institute for the Study of War, a Washington DC-based think tank, said: "The Russian conventional military continues to underperform badly, although it may still wear down and defeat the conventional Ukrainian military by sheer force of numbers and brutality."
Ukraine insisted Russia's losses are many times higher but did not disclose its own military casualties.
"Total resistance … This is our Ukrainian trump card and this is what we can do best in the world," Ukrainian presidential aide Oleksiy Arestovich said in a video message, recalling guerilla actions in Nazi-occupied Ukraine during World War II.
The UN Human Rights Council on Friday condemned alleged rights violations by Russia in its invasion of Ukraine and agreed to set up a commission to investigate them, including possible war crimes.
The commission, set up for an initial period of one year and tasked with producing a report by early 2023, will work alongside a large, existing United Nations rights team for Ukraine which has 60 members.
ABC/wires
