Around 1,700 ⁠apartment buildings in the Ukrainian capital Kyiv were still without heating following a Russian missile and drone attack earlier this week, Kyiv Mayor Vitalii Klitschko said on Sunday.

Moscow has sharply intensified bombardments ‍of Ukraine's energy system since it invaded its ‍neighbor in 2022.

Russia launched a vast attack on Ukraine's energy system on Saturday, rocking Kyiv ⁠with explosions overnight, leaving 1.2 million properties without power countrywide during sub-zero winter temperatures.

"Russia’s main targets right now are our ​energy sector, critical infrastructure, and residential buildings," Ukraine's President Volodymyr Zelenskyy said on X.

This week alone, he said Russia had launched more ‍than 1,700 attack drones, over 1,380 guided aerial bombs and 69 missiles ⁠on Ukraine.

Every massive attack by Russia could have a devastating impact, said Zelenskyy, who on Sunday visited Lithuania.

"We are working with every leader to strengthen Ukraine. Everyone must clearly understand the ⁠threat coming from Russia," he ​said.

Deputy Prime Minister ⁠Oleksiy Kuleba said on Saturday that more than 3,200 of Kyiv's buildings were ‍without heating late that evening, down from 6,000 in the morning.

"Since yesterday evening, ‌utility workers and energy companies have restored heat supply to more than 1,600 buildings. They are continuing to work to ⁠restore services ​to the homes of ‍Kyiv residents," Klitschko said on Telegram.

The large-scale attack on the Ukrainian capital took place just as ‍Ukrainian, Russian and American negotiators were discussing options in Abu Dhabi for ending the war.