Russia has hit Ukrainian energy infrastructure throughout the nearly four-year war, but Kyiv says this winter has been the toughest with hundreds of Russian drones and missiles overwhelming air defences during particularly fierce frosts.

"This week alone, the Russians have launched more than 1,700 attack drones, over 1,380 guided aerial bombs, and 69 missiles of various types," the president said as he arrived in Vilnius.

"That is why missiles for air defence systems are needed every day, and we continue working with the United States and Europe to ensure stronger protection of our skies," he added.

Russian bombardments have hit Kyiv particularly hard, forcing half a million people to evacuate.

"There are currently 1,676 high-rise apartment buildings in Kyiv without heating following the enemy's attack on Kyiv city on January 24," said mayor Vitali Klitschko.

Sub-zero temperatures and repeated air strikes have slowed efforts by repair crews working to restore heating and electricity.

In Vilnius, Zelensky was taking part in a ceremony to commemorate the 1863 uprising in Poland and Lithuania against Tsarist Russia.

Polish President Karol Nawrocki, who also attended the event, drew a parallel between the Russian invasion of Ukraine and past struggles for freedom by peoples in the Russian empire.

"The message of these celebrations is that by looking to the past for what we have in common, it's easier today to face the problems ahead of us. Especially in an era of the revival of imperial Russia," his office said on X.

Poland and Lithuania are among the staunchest supporters of Kyiv in the European Union, and both have recently supplied hundreds of generators to the war-torn country.

US-brokered talks with Russia and Ukraine on Washington's plan to end the war ended with no apparent breakthrough on Saturday.

Still, Zelensky said the negotiations were "constructive", and both sides have agreed to meet in Abu Dhabi again next week.