KYIV - Ukraine said Wednesday it had shot down more than a dozen Iranian-made drones in Moscow's latest assault on Kyiv.

The attack came as the Kremlin promised no let-up to fighting over Christmas and as Ukrainian President Volodymyr Zelensky urged European leaders to assist in setting up a court to try Russian leaders over the war.

"The terrorists started this morning with 13 Shaheds," Zelensky said, referring to the Iran-made weapons.

"All 13 were shot down," he added, urging residents to heed air raid sirens.

The national energy provider Ukrenergo said no electricity facilities had been damaged in the attack, crediting Ukrainian air defenses for their "brilliant" work.

Such defense forces appeared set for a boost with ally Washington preparing to send a batch of Patriot missile defense batteries to Kyiv.

Ukraine has been subjected to frequent and deadly aerial attacks in the 10 months since Russia invaded Ukraine in February and tried to capture the capital.

But since a series of key battlefield setbacks this summer and autumn, Russia began systematically targeting critical infrastructure in Ukraine.

With temperatures dropping, the missile and drone attacks have disrupted electricity, water and heat to millions of Ukrainians.

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'Nearly 7 million children' at risk

The strikes targeting energy infrastructure have piled pressure on Ukraine's power grid, whose operators have for weeks been forced to implement rolling blackouts.

That left "nearly seven million children without sustained access to electricity, heating and water, putting them at increased risk", UNICEF, the UN children's agency said Wednesday.

Explosions rang out over central Kyiv and AFP journalists later saw law enforcement and emergency service workers inspecting metal fragments at a snow-covered impact site.

City officials said debris from the downed drones had damaged residential homes and a local administrative building.

No one was reported injured or killed, but residents cleaning up broken window glass and assessing damage vented their frustration at the Russian barrages.

"Winter is coming, how can people survive?" asked Svetlana, a local resident who described how a drone rumbled over homes before she heard a loud explosion.

"They do not let Ukrainians live."

The latest round of attacks came a day after dozens of countries and international organisations meeting in Paris responded to Zelensky's plea to help the country withstand Russia's onslaught on its energy grid with 1 billion euros ($1.1 billion).

• Ukraine secures 1 billion euros in aid 'to get through winter'

In a video message from Kyiv, Zelensky said Ukraine needed assistance for its battered energy sector and spare parts for repairs, high-capacity generators, extra gas and increased electricity imports.

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Foreign Minister Dmytro Kuleba called on Ukraine's allies to provide his country with more weapons to help it "fight through the winter" and sustain Kyiv's military advances.

The United States has been a major contributor to Ukraine's arsenal throughout the war, and a US official confirmed to AFP that Washington is finalising plans to send batteries of the advanced Patriot missile system to Ukraine.

The public announcement on the Patriot, described by the US Army as its "most advanced air defense system," could come as soon as Thursday.

US citizen freed

Ukraine separately said Wednesday it had secured the release of a US citizen as well as 64 Ukrainian members of the military in its latest prisoner swap with Russian forces.

Russia's state-run TASS news agency earlier reported that the American, Suedi Murekezi, had been arrested in the eastern Donetsk region of Ukraine in June and charged with attending anti-Russian protests.

After nearly 10 months of fighting, Russia has yet to fulfil any of its stated key goals in what it refers to as its "special military operation" in Ukraine, including seizing the capital or the eastern Donbas region.

But the Moscow-installed leader of Ukraine's Donetsk province on Wednesday called for Russia to widen its goals and annex two more areas of Ukraine: the Black Sea region of Odessa and Chernigiv in the north.

Kremlin spokesman Dmitry Peskov said a ceasefire was not on Moscow's agenda, and that it had not received proposals from Kyiv to pause fighting during the upcoming holiday period.

Meanwhile on Wednesday, Zelensky accepted the European Union Sakharov Prize for human rights on behalf of Ukraine's people.

As he accepted the EU's top rights award, he urged Europe to help set up a tribunal swiftly to try Russia's leadership for the "crime of aggression".

Zelensky also warned the International Olympic Committee against welcoming back Russian athletes to international competition, after US Olympic officials signaled they were open to the idea.

The only response is "the complete isolation of the terrorist state on the international stage," Ukraine's leader told IOC president Thomas Bach in a statement.

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© Agence France-Presse