The United Nations has called on Russia to stop its attacks on Ukraine's energy sites, which have plunged entire cities into darkness in the coldest winter of the four-year war.
Russia has stepped up strikes on Ukraine's power and heating infrastructure, and conducted another nationwide attack on energy facilities overnight that killed two people.
"The relentless attacks by the Russian Federation on energy infrastructure across Ukraine are depriving an already long-suffering civilian population of adequate warmth, water and electricity in an unbearably bitter and dark winter," UN rights chief Volker Turk said in a statement.
He said civilians had faced continual bombardment and now had to face temperatures as low as minus 20C.
"Last night, the Russian Federation again carried out a large-scale attack targeting energy infrastructure across Ukraine. Hundreds of thousands of civilians woke up without electricity and heating," said Mr Turk.
"The targeting of civilian infrastructure is prohibited under international humanitarian law. I call upon the Russian Federation to immediately cease these attacks."
The UN high commissioner for human rights said the consequences of such strikes impacted all areas of civilian life.
Mr Turk said millions of households were struggling with a few hours of electricity every day, while unheated schools have been forced to close and access to medical care has been hampered.
Ukraine said the strikes are an attempt to sap morale and weaken Ukrainians' resistance.
There were loud blasts in Kyiv overnight and explosions lit up the sky, as Ukrainian air defence systems fended off the Russian barrage.
"After last night's massive attack, due to damage to critical infrastructure targeted by the enemy, nearly 2,600 more buildings in the capital have been left without heat," Kyiv mayor Vitali Klitschko said.
We need your consent to load this rte-player contentWe use rte-player to manage extra content that can set cookies on your device and collect data about your activity. Please review their details and accept them to load the content.Manage Preferences
He added that two people had been wounded in the capital overnight.
More than 1,000 of the capital's approximately 12,000 apartment blocks were already without heating after massive Russian attacks over the last few weeks.
Russia launched 24 missiles and 219 drones at the war-torn country, Ukraine's air force said, adding that its air defence units had downed 16 missiles and 197 drones.
Two people were killed in the eastern Ukrainian town of Lozova, where the attack cut power to residents and forced authorities to use alternative power sources for critical infrastructure, a local official said.
The attack also wounded four people in the central city of Dnipro, and cut heating to 10,000 customers, Restoration Minister Oleksiy Kuleba said.
"This is yet another attempt to deprive Ukrainians of basic services in the middle of winter. But restoration efforts continue nonstop," Mr Kuleba added.
In the southern Odesa region, the attacks wounded one person, the state emergency services said, while Mr Kuleba said around 300,000 had been left without water supplies.
Russia meanwhile said it repelled a missile attack in the Volgograd region but that debris ignited a fire at a military facility and prompted the evacuation of a nearby village.
EU support for Ukraine 'critically important' - Kyiv mayor Vitali Klitschko
UK pledges over €600m in weapons to Ukraine
Meanwhile, the UK has pledged hundreds of millions of euro in air defences for Ukraine to help stave off Russian attacks on the country's power and heating systems.
The British defence ministry said some £150m (€172m) would go to a NATO scheme backed by US President Donald Trump to buy American weaponry for Ukraine.
London will also send 1,000 British-made lightweight missiles worth more than £390m (€447m) to Kyiv.
British Defence Minister John Healey said Ukraine's allies "are more committed than ever to supporting Ukraine" as Russia's war nears the start of its fifth year.
The announcement came as NATO defence ministers met in Brussels to discuss ramping up support to Ukraine.
Ferocious Russian bombardments on the war-torn country's energy grid have seen heating and power cuts for swathes of the country during freezing winter conditions.
"It's just terrorism against the civilian population of Ukraine," said German defence minister Boris Pistorius.
"So it is necessary to ramp up the support for Ukraine in terms of self-defence."
Read more:
Russia attempted to 'fully block' WhatsApp, app says
Ukrainian skeleton athlete Vladyslav Heraskevych banned over helmet marking war
Plants in Ukraine's national garden wither due to frost and power cuts
