Russian forces in Ukraine have seized Europe's biggest nuclear power plant in an assault that caused alarm around the world.
Fighting also rages elsewhere in Ukraine, as troops besiege and bombard several cities in the second week of an invasion launched by Russian President Vladimir Putin.
The capital Kyiv, in the path of a Russian armoured column that has been stalled on a road for days, came under renewed attack, with explosions audible from the city centre.
The southeastern port city of Mariupol - a key prize for the Russian forces - has been encircled and shelled. Its mayor has said it had no water, heat or electricity and is running out of food after five days under attack.
"We are simply being destroyed," Mayor Vadym Boychenko said.
However, NATO allies have also rejected Ukraine's appeal for no-fly zones, saying they were increasing support but that stepping in directly would lead to a broader, even more brutal European war.
Ukrainian President Volodymyr Zelensky has criticised NATO's decision, saying the Western military alliance knew further Russian aggression was likely.
"Knowing that new strikes and casualties are inevitable, NATO deliberately decided not to close the sky over Ukraine," he said in a video published by the presidency.
"Today the leadership of the alliance gave the green light for further bombing of Ukrainian cities and villages, refusing to make a no-fly zone."
Putin's actions have drawn almost universal worldwide condemnation and Western countries have imposed heavy sanctions in an effort to squeeze the Russian economy.
A humanitarian disaster is also unfolding, with more than one million people seeking refuge in western Ukraine and in neighbouring countries. Thousands of people are believed to have been killed or wounded since the invasion started on 24 February.
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The attack on the Zaporizhzhia nuclear power plant brought the conflict to a perilous moment. As shells hit the area, a blaze broke out in a training building - triggering a spasm of alarm around the world before the fire was extinguished and officials said the facility was safe.
The US Ambassador to the United Nations, Linda Thomas-Greenfield, said the world had narrowly averted a nuclear catastrophe.
The attack reflected a "dangerous new escalation" in Russia's invasion, she said during an emergency UN Security Council meeting, warning that "imminent danger" persisted and demanding assurances from Moscow that such an assault will not happen again.
An official at Energoatom, the Ukrainian state nuclear plant operator, said fighting had ceased and radiation levels were normal. But his organisation no longer had contact with the plant's managers or control over its nuclear material, he said.
International Atomic Energy Agency chief Raphael Grossi said the plant was undamaged from what he believed was a Russian projectile. Only one of its six reactors was working, at around 60% of capacity.
Russia's defence ministry also said the plant was working normally. It blamed the fire on an attack by Ukrainian saboteurs and said its forces were in control.
The plant and adjacent territory were now being guarded by Russian troops, Moscow's envoy to the United Nations said.
Appeal spurned
Germany's Chancellor Olaf Scholz phoned Putin and demanded he call off the war. But NATO allies meeting in Brussels have rejected Ukrainian President Volodymyr Zelensky's demand for no-fly zones.
"We are not part of this conflict," NATO Secretary-General Jens Stoltenberg told a news conference.
"We have a responsibility as NATO allies to prevent this war from escalating beyond Ukraine because that would be even more dangerous, more devastating and would cause even more human suffering."
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US Secretary of State Antony Blinken also rejected a no-fly zone, saying the only way to implement one over Ukraine would be for NATO forces to shoot down Russian planes.
Moscow denies targeting civilians in Ukraine and says its aim is to disarm its neighbour, counter what it views as NATO aggression and capture leaders it calls neo-Nazis. Ukraine and its Western allies call that a baseless pretext for a war to conquer a country of 44 million people.
Minister for Foreign Affairs Simon Coveney lamented "the images we see of apartment blocks in working class areas outside of cities with half of buildings gone, in smouldering rubble."
More EU sanctions are coming, potentially including a ban on Russian-flagged ships in European ports and blocking imports of steel, timber, aluminium or coal, he said.
Defending Kyiv
In Kyiv's Borshchahivka neighbourhood, the twisted engine of a cruise missile lay in the street where it had apparently been downed overnight by Ukrainian air defences.
Russian troops "all should go to hell," said Igor Leonidovich, 62, an ethnic Russian who moved to Ukraine 50 years ago as a boy.
"For the occupiers, it is getting worse and worse, every day."
A Ukrainian presidential adviser said an advance had been halted on the southern port of Mykolayiv after local authorities said Russian troops had entered it. If captured, the city of 500,000 people would be the biggest yet to fall.
Adviser Oleksiy Arestovych said: "We can feel cautious optimism about the future prospects of the enemy offensive - I think that it will be stopped in other areas also."
Russian forces have made their biggest advances in the south, where they captured their first sizeable Ukrainian city, Kherson, this week. Bombing has worsened in recent days in the northeast cities of Kharkiv and Chernihiv.
Ukrainians have been fleeing west, many crowding into Lviv near the Polish border.
Europe's largest nuclear plant at centre of Russia-Ukraine war
James Elder of the United Nations children's agency said doctors in Lviv were preparing a system to identify children in case of mass casualties.
"A green dot means fine over here, a yellow dot means critical support. They are learning a black dot means the child won't make it," he said.
Clampdown
In Russia, where Putin's main opponents have largely been jailed or driven into exile, the war has led to a further crackdown on dissent.
Authorities have banned reports that refer to what it terms a "special military operation" as a "war". Anti-war demonstrations have been squelched with thousands of arrests.
The BBC has stopped reporting in Russia after parliament passed a law there imposing a jail term of up to 15 years for anyone found to be intentionally spreading "fake" news.
Russia earlier cut access to several foreign news organisations' websites, including the BBC, Voice of America and Deutsche Welle, for spreading what it said was false information about its war in Ukraine.
Russia also blocked Facebook in response to what its communications regulator said were restrictions on access to Russian media on the platform. Access to Twitter has also been restricted.
