The United States and its allies have slammed Russia at an emergency UN Security Council meeting over the shelling and nighttime seizure of the Zaporizhzhya nuclear power plant in southeastern Ukraine.

US Ambassador to the United Nations Linda Thomas-Greenfield said the world “narrowly averted a nuclear disaster” when Russian forces fired on the facility, causing a fire that burned overnight.

“Russia’s attack last night seriously endangered Europe’s largest nuclear power plant. He was incredibly reckless and dangerous. And he threatened the safety of civilians across Russia, Ukraine and Europe,” Thomas-Greenfield told the council on March 4.

British Ambassador to the UN, Barbara Woodward, said: “This must not happen again. Even in the midst of an illegal invasion of Ukraine, Russia must stay away from nuclear facilities and protect their safety.”

Russia’s UN envoy Vasily Nebenzya dismissed their statements, calling the Security Council meeting another attempt by the Ukrainian authorities to create “artificial hysteria”. “Currently, the Zaporizhia nuclear power plant and the adjacent area are guarded by Russian troops,” he said.

Ukraine had previously described the seizure of the power plant as “nuclear terrorism” and warned that the danger at the power plant was not over.

WATCH: Employees at Ukraine’s Zaporizhia and Chernobyl nuclear sites are being held by Russian forces and working under a gun barrel, according to the former head of Ukraine’s nuclear inspection.

Ukrainian President Volodymyr Zelenskyy described the attack on the plant the day before on March 4 as “an act of terrorism of unbelievable proportions”.

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The attack, which the International Atomic Energy Agency (IAEA) said caused the fire, came as Russian forces stepped up their military campaign through Ukraine. Kyiv was shelled again overnight and Russian troops are said to have been in the center of Kherson on the Black Sea coast.

Heavy fighting continued on the outskirts of another strategic port, Mariupol, with power, heat and water cut out along with most telephone services.

Zelenskiy and other Ukrainian officials devastated Russia for the attack on the Zaporizhzhya power plant.

“This station alone could be like six Chernobyl [tragedies]Zelenskyy warned, saying the Russian tanks “knew what they were shooting at” and accused them of erasing the 1986 Chernobyl nuclear disaster from their memories.

Zelenskyi said it was a very dangerous night for all of humanity after a fire in Zaporizhzhya got out of control. According to Ukrainian government officials, the fire started after a projectile struck a nuclear training center inside the facility.

Firefighters put out the blaze in the morning, and nuclear officials from around the world said no leak had been spotted.

The US embassy in Ukraine called the Russian attack on the plant a “war crime,” and Pentagon spokesman John Kirby said it shows how ruthless the Russian invasion was.

“It just increases the magnitude of a potential catastrophe to a level that nobody wants to see,” he told CNN.

Russian forces caused alarm last week when they seized the decommissioned Chernobyl nuclear power plant days after Russian President Vladimir Putin ordered the unprovoked invasion of Ukraine.

Yuriy Kostenko, Ukraine’s former nuclear safety minister, said what Russian forces were doing in Chernobyl and Zaporizhia was “nuclear terrorism” and international law obliges all countries to stand up to it, he added in an apparent reprimand to a protocol to the Geneva Convention restricting military attacks on nuclear facilities.

“Therefore, Ukraine must not demand a no-fly zone from NATO, but demand it. It would be a defense of Ukraine and Europe as a whole from international nuclear terrorism,” he said.

According to diplomats, the UN Security Council has scheduled an emergency meeting for March 4.

Russian President Vladimir Putin told Chancellor Olaf Scholz in a phone call that Russia is ready for dialogue if all its demands are met, the Kremlin said. This includes demilitarizing Ukraine, accepting Moscow’s sovereignty over Crimea and ceding territory to Russian-backed separatists in the east, the Kremlin said in its reading of the call.

WATCH: A residential building in Irpin, northwest of Kyiv, was hit by shells as Russian forces continued to attack districts around the Ukrainian capital. An amateur video posted to social media on March 4 showed shells hitting the skyscraper.

Russian and Ukrainian negotiators met for a second round of talks on March 3 and reached a tentative agreement on establishing safe corridors allowing civilians to leave besieged Ukrainian cities and delivering humanitarian aid. They also agreed to continue talking about ways to negotiate an agreement.

Ukrainian Foreign Minister Dmytro Kuleba on March 4 accused Russian soldiers of bombing and raping civilians in Ukrainian cities, without providing any evidence to support the allegation.

RFE/RL and international agencies have been unable to independently confirm Kuleba’s rape allegations.

“When bombs fall on your cities, when soldiers rape women in the occupied cities – and unfortunately we have numerous cases of Russian soldiers raping women in Ukrainian cities – it is of course difficult to talk about the efficiency of internationality right”, Kuleba said in English at an event at Chatham House in London.

After a meeting of foreign ministers in Brussels, NATO Secretary General Jens Stoltenberg said the alliance had observed the use of cluster bombs in Ukraine.

In Kherson, where Russian troops had reached the city center and were reportedly attempting to establish local control on March 3, the regional administration said Russian actions had shut down several telephone networks.

The port city of Mariupol remained “under siege” with Ukrainian forces fighting to avoid an encirclement of the city by Russian forces, Ukraine’s presidential aide Oleksiy Arestovich said.

The cities of Kharkiv and Okhtyrka were under fire, but the defenses held, he said.

Arestovich credited the defense of these cities with “gaining time” and diverting Russian forces from other targets, including Kyiv.

The head of the region, Dmytro Zhyvytskiy, warned that water and electricity had been lost since an airstrike destroyed the Okhtyrka power plant. He also said Russian troops seized ground in Enerhodar near the Zaporizhia nuclear power plant in south-eastern Ukraine.

The regional branch of Ukraine’s state administration on March 4 raised the death toll to at least 47 after a Russian airstrike in the city of Chernihiv, a city of around 300,000 near the northeastern border with Russia.

Images of severely damaged residential buildings and a burning oil depot in Chernihiv circulated.

WATCH: Many Russians are fed daily by the media Kremlin propaganda that obscures the horrific destruction and human cost of their country’s invasion of Ukraine. So how did ordinary Russians in Perm and Vladivostok react when Current Time reporters showed them some pictures?

Protests against the Russian occupation, meanwhile, continued early on March 4 in the Zaporizhzhya region, a correspondent for RFE/RL’s Ukrainian service said, including in Primorsk and Melitopol, where a local organizer said thousands had turned out in a central square.

Regional authorities said the Russian military surrounded a local television tower in Melitopol and began broadcasting Russian programs.

Meanwhile, Russian President Vladimir Putin gave a speech in which he claimed he had no “bad intentions” towards Russia’s neighbors.

“I would like to emphasize once again: we have no, as we have already said, bad intentions towards our neighbors,” said Putin. “I would advise them not to increase tensions, not to introduce restrictions. We are delivering on all of our promises and will continue to deliver on them.”

Putin on February 24 declared his unprovoked large-scale invasion of Ukraine, said Moscow’s goal was Ukraine’s “demilitarization” and accused Kyiv of extremism with labels he has used in the eight years since he occupied Ukraine’s Crimea and with the Arms support has begun to be routinely used by separatists in eastern Ukraine.

As international financial and other sanctions mounted and the United Nations’ top human rights body voted 32-2 in favor of a resolution to set up a body to monitor human rights in Ukraine, Putin blamed other countries for Russia’s isolation.

“If some [countries] If they don’t want to work with us at the international level, they will harm themselves and us, but we will solve all the problems ourselves,” Putin said.

He urged other countries to “normalize” relations with Russia, whose invasion was overwhelmingly condemned by UN membership this week.

Kremlin spokesman Dmitry Peskov urged Russians, thousands of whom have been arrested over anti-war protests while media and other anti-disturb measures have been tightened, to “crowd” around Putin.

Thousands of people are believed to have been killed and more than a million Ukrainians have fled west amid a burgeoning refugee crisis since Putin launched his invasion.

Ukraine’s Children’s Rights Commissioner Darya Herasymchuk said on March 4 that at least 28 children have been killed and 64 injured in the conflict so far.

she said Around 1.5 million children live in the hardest-hit areas, citing “destroyed maternity hospitals, kindergartens and schools”.

With reports from the Ukrainian service of RFE/RL and Reuters