An overnight Russian bombardment of Kiev left thousands of residential buildings and the parliament without heat and water in temperatures of -14 degrees Celsius on Tuesday, just as the Ukrainian capital was trying to restore vital services destroyed in earlier attacks.
The barrage of hundreds of drones and missiles, which targeted energy facilities across Ukraine, killed at least one 50-year-old man near Kiev.
More than half a million people have been evacuated from the capital this month as Russia launched its strongest attack on the capital's energy infrastructure during the war, the city's mayor, Vitali Klitschko, told AFP.
AFP journalists in the capital heard airstrike sirens and explosions, while Ukrainian air defense systems responded to drones and missiles.
Sheltering in a metro station in central Kiev, Marina Sergienko, a 51-year-old accountant, said she thought the repeated Russian attacks, which have left millions of people in the cold and darkness over the past few weeks, had a clear purpose.
"To tire people out, to bring things to a critical point so that there is no strength left, to break our resistance," she told AFP, taking shelter alongside dozens of other Kiev residents wearing hats and coats.
Foreign Minister Andriy Sybiga harshly attacked Russian President Vladimir Putin, saying: "War criminal Putin continues to wage a genocidal war against women, children and the elderly."
He said Russian forces had targeted energy infrastructure overnight in at least seven regions and called on Ukraine's allies to strengthen its air defense systems.
Zelensky suggested he would skip the World Economic Forum taking place in Switzerland to deal with the fallout from the strike.
But he kept open the possibility of going to the meeting of world leaders in the ski resort of Davos, if agreements with the United States on possible economic and security support after the war were ready to be signed.
Kiev's air force said Russia shot down about 339 long-range combat drones and 34 missiles during the nighttime attacks.
"The performance of the Air Force against the Shahed is unsatisfactory," the Ukrainian president said, referring to the Iranian-designed drones used by Russia.
Zelensky, who had recently complained about slow arms deliveries, said Ukraine had received a shipment of ammunition for air defense systems just the day before.
The bombing occurred about 10 days after the most significant Russian attack on Kiev's energy grid since its occupation almost four years ago.
That strike, at dawn on January 9, left half the capital without heat and many residents without electricity for days in sub-zero temperatures, prompting Klitschko to issue a rare call for residents to evacuate.
"Not everyone has the opportunity to leave the city, but for now the population has decreased," Klitschko told AFP in an interview, specifying that 600,000 people had been displaced from the capital of about 3.6 million inhabitants.
Most of the buildings shut down on Tuesday were those affected on January 9.
Schools have been closed until February and street lights have been dimmed in an effort to conserve energy resources.
"In Kiev alone, by the evening more than a million consumers will be without electricity," Zelensky said, adding that more than 4,000 apartment blocks are still without heating.
That's about half of the capital's apartment blocks, and city authorities previously said much of Kiev was without running water.
The Ukrainian parliament building was also blocked, parliament speaker Ruslan Stefanchuk said in a video message.
Authorities in the western region of Rivne said a separate attack there had damaged "critical infrastructure", leaving 10,000 households without electricity.
The head of the southern Odessa region added that a Russian drone had crashed into a residential building and that energy facilities had been hit.
The power grid supplying the defunct Chernobyl nuclear power plant was also hit, temporarily cutting off electricity needed to maintain the plant. It was later reconnected to the grid, said plant director Sergiy Tarakanov.
Russia has been hitting Ukraine's energy sector since the beginning of its invasion, in what Kiev calls an attempt to lower morale and weaken Ukrainian resistance.
The Kremlin says it is only targeting Ukrainian military facilities and has blamed Kiev for continuing the war because it refuses to accept its demands for peace.
The Russian Defense Ministry said on Tuesday that it had carried out airstrikes on facilities supporting the Ukrainian military.
The International Criminal Court has issued arrest warrants for two senior Russian military officials linked to attacks on Ukraine's energy grid.
The court said this constituted a war crime as it was designed to harm Ukrainian civilians.
Due to wartime sensitivities, Kiev does not say which energy facilities were damaged or destroyed in the Russian attacks.
