The mayor of the Ukrainian town of Energodar said a column of Russian troops was headed toward the nearby Zaporizhzhia nuclear power plant, Europe's largest, late on Thursday after they had already taken control of the Nuclear facility in Chernobyl last week
"Loud shots can be heard in the town," said Mayor Dmytro Orlov in an online post.
International Atomic Energy Agency chief Rafael Grossi called for fighting to stop there.
"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 UN watchdog said in a statement.
After the second round of talks, Russia and Ukraine have agreed on the need to set up humanitarian corridors and a possible ceasefire around them for fleeing civilians, both sides said on Thursday, in their first sign of progress on any issue since the invasion.
Russian negotiator Vladimir Medinsky said the talks had made "substantial progress," Russian invasion forces surrounded and bombarded Ukrainian cities as the conflict entered its second week.
The Ukrainian negotiator said the talks had not yielded the results Kyiv hoped for, but the two sides had reached an understanding on evacuating civilians.
After the talks at an undisclosed location, Ukrainian presidential adviser Mykhailo Podolyak said they envisaged a possible temporary ceasefire to allow the evacuation of civilians and the creation of humanitarian corridors.
"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," he said.
They had also reached an understanding on the delivery of medicines and food to the places where the fiercest fighting was taking place. The negotiators will meet again next week, the Belarusian state news agency Belta quoted Podolyak as saying.
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Residential areas destroyed by Russian bombing in Chernihiv in northern Ukraine on Thursday
(Photo: Reuters)
Russian forces are trying to blockade the southeastern Ukrainian port city of Mariupol, knocking out power, water and heating supplies with bombardment that is preventing residents from fleeing, local authorities said as the mayor said his city was being destroyed.
As Russia's invasion of Ukraine enters its second week, the port city is seeing some of the fiercest fighting with constant shelling for the past 24 hours, Mayor Vadym Boichenko said in a video broadcast.
The city authorities likened the Russian onslaught to Nazi Germany's protracted deadly siege of the then-Soviet city of Leningrad during World War Two.
"Mariupol remains under fire. Women, children and the elderly are suffering. We are being destroyed as a nation. This is genocide of the Ukrainian people," the city's council said in a statement.
Ukrainian soldiers and civilians kept up their resistance to the Russian onslaught, and the capital Kyiv and other main cities remained in their hands.
But the humanitarian crisis deepened, with the United Nations saying one million people had now fled their homes. Most were seeking refuge in Poland and other neighbors to the west.
Those who stayed were enduring shelling and rockets strikes on several cities, often on residential areas. Swathes of Kharkiv, Ukraine's second city with 1.5 million people, have been blasted into rubble.
Ukrainian President Volodymyr Zelenskiy said earlier Kyiv and Moscow could find a way out of the war if the Kremlin treated Ukraine on an equal footing and came to talks with a will to negotiate in good faith.
"There are things in which some compromises must be found so that people do not die, but there are things in which there are no compromises," Zelenskiy said in a televised interview, saying he was willing to have an open conversation with Putin.
Western military analysts believe that a Russian battle plan that aimed for a swift advance and capture of 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.
In Washington, a U.S. official said Russian troops were still 25 km out of Kyiv city center. They were also just outside of Kharkiv now, the official said.
The fate of Kherson, a southern Dnipro River port, was not clear. Russian tanks had entered on Wednesday and it was reported to have been captured. But the U.S. official said Washington believed there was still fighting in Kherson and it was not ready to say it is in Russian hands.
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 on the highway north of Kyiv, 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 (40 miles) northwest of Kyiv where local people repelled a Russian assault, burnt-out hulks of destroyed Russian armor 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 armored personnel carrier.