Powerful explosions shook the area around Ukraine’s Zaporizhzhia nuclear power plant Saturday and again Sunday morning, with the U.N.’s atomic energy chief calling the fighting between Russia and Ukraine in the region “extremely disturbing.”

The blasts abruptly ended a period of relative calm at the facility, Europe’s largest nuclear plant.

Rafael Mariano Grossi, the director-general of the International Atomic Energy Agency, said, “Whoever is behind this, it must stop immediately. As I have said many times before, you're playing with fire!”

Grossi appealed to both Russia and Ukraine to urgently agree to implement a nuclear safety and security zone around the nuclear facility, although his earlier appeals have not resulted in any new controls on fighting in the region.

The IAEA said the attacks at Zaporizhzhia damaged some buildings, systems and equipment, but none threatened nuclear safety and security. There have been no casualty reports.

As bitter winter weather hits Ukraine, Russia has been attacking the Ukrainian power grid and other key infrastructure from the air, causing widespread blackouts for millions of Ukrainians. In the Zaporizhzhia region alone, the Ukrainian presidency said, Russian forces shelled civilian infrastructure in about a dozen communities, destroying 30 homes.

One person was wounded, and 20 buildings were damaged in the shelling of Nikopol, a city across the river from the Zaporizhzhia plant, the report said.

Russia hit three districts in the northern Kharkiv region — Kupyansk, Chuguiv and Izyum — with artillery fire in the past day, while in the eastern Luhansk and Donetsk regions, Russian shelling killed one person in Donetsk and damaged power lines, according to Ukrainian President Volodymyr Zelenskyy's office.

Meanwhile, Britain’s Defense Ministry said in its daily intelligence update Sunday that Russia’s recent withdrawal from the southern city of Kherson “was conducted in relatively good order” and its success “is likely partially due to a more effective, single operational command under General Sergei Surovikin.”

The ministry said Russian vehicle losses were likely in the tens rather than the hundreds, while any equipment left behind was “successfully destroyed by Russian forces to deny it to Ukraine.”

The report warned, however, that the Russian force “remains riven by poor junior and mid-level leadership and cover-up culture.”

U.S. Defense Secretary Lloyd Austin said Saturday that Ukraine's defense has global implications. At the Halifax International Security Forum in Canada, he warned that Russia's invasion of Ukraine offers a preview of a world where nuclear-armed countries could threaten other nations.

“Putin's fellow autocrats are watching,
Austin said. “And they could well conclude that getting nuclear weapons would give them a hunting license of their own. And that could drive a dangerous spiral of nuclear proliferation.” Austin also said Moscow's efforts to gain support from countries such as Iran and North Korea create new security challenges for the United States and its allies.

Earlier, the Pentagon's top policy adviser, Colin Kahl, said Russia is trying to deplete Ukraine's air defenses and achieve dominance over Ukrainian skies.

Russia has been pummeling Ukraine with missile strikes throughout the past week, the heaviest wave since Moscow invaded nine months ago.

In Kyiv, people woke up Saturday to several inches of snow. Ukrainian authorities in the capital are warning of a “complete shutdown,” as subzero temperatures grip the country.

Russian airstrikes have inflicted heavy damage on the energy grid of the Ukrainian capital while they continue to pound Ukraine — from Kyiv in the north to Odesa in the south — crushing almost half of Ukraine's energy system, Ukrainian Prime Minister Denys Shmyhal said.

“They are determined to destroy our power grids,” said Andriy Yermak, head of the Office of the President of Ukraine, in a speech at the Halifax forum.

“The calculation is simple: a humanitarian catastrophe. Moscow always considers frost and darkness as its allies. It always uses the deprivation of basic life needs as a war tool. It always despises humanitarian law. Russia is a terrorist state,” Yermak said.

Amid freezing temperatures, difficulties with energy supplies persist throughout Ukraine, Zelenskyy said Saturday, in his nightly video address.

"Energy workers are doing everything possible to give people a normal life,” he said.

He added transport connections are being restored in Kherson.

“There is the first train from Kyiv. We create new opportunities for people every day,” Zelenskyy said.

In message earlier Saturday, Zelenskyy also addressed the annual Halifax meeting.

“The end of the war doesn't guarantee peace. Russia is now looking for a short truce, a respite to regain strength… such a respite will only worsen the situation,” he said. (VOA)

•PHOTO: FILE - Reactors of the Zaporizhzhia Nuclear Power Plant, Europe's largest, are seen from the town of Nikopol, in Ukraine's Dnipropetrovsk region, Nov. 7, 2022, amid Russia's ongoing invasion of its neighbor.

Update news