Russian missiles have hit three Ukrainian cities, including its two biggest, killing at least seven people and destroying apartment buildings.
It comes after Moscow shunned any deal backed by Kyiv and its western allies to end the nearly two-year-old war.
The barrage included more than 40 ballistic, cruise, anti-aircraft and guided missiles, officials reported, in what the United Nations (UN) said appeared to be the heaviest bombardment since early January, when hundreds of Ukrainian civilians were killed.
Ukraine’s air force, whose defences include western-supplied systems, said it intercepted 21 of the missiles.
The attacks keep Ukrainians on edge while the 930-mile frontline has barely budged.
Both sides’ inability to deliver major gains on the battlefield has pushed the fighting toward trench and artillery warfare.
Analysts say Russia stockpiled missiles at the end of last year to press a winter campaign of aerial bombardment.
The recent Russian bombardment was “an alarming reversal” of a trend last year which saw a drop in civilian casualties from Kremlin attacks, the UN said.
More than 10,000 civilians have been killed and nearly 20,000 injured since Russia’s full-scale invasion in February 2022, the UN said.
Tuesday’s onslaught in Kharkiv, in north-eastern Ukraine, killed six people and injured 57, including eight children, the UN said.
The missiles damaged about 30 residential buildings and shattered hundreds of windows in icy weather, regional governor Oleh Syniehubov said.
Russia used S-300, Kh-32 and hypersonic Iskander missiles in the attack, he said.
A five-storey apartment building appeared to have been directly hit by several missiles at around dawn, the UN Human Rights Mission in Ukraine said.
An unknown number of people were trapped in the rubble with the temperature falling to minus 7C, said Kharkiv mayor Ihor Terekhov.
Kharkiv, about 18 miles from the border, has often felt the brunt of Russia’s winter campaign of long-range strikes which commonly hit civilian areas.
Four districts of Kyiv came under an attack that injured at least 20 people, including a 13-year-old boy, according to mayor Vitalii Klitschko.
Officials corrected initial reports that a civilian had been killed in the capital, saying the wounded person was admitted to hospital and on life support.
UN staff visited a Kyiv neighbourhood with a damaged residential building, a school, a sports centre and a children’s nursery.
A missile also killed a 43-year-old woman and damaged two schools and eight high-rise buildings in Pavlohrad, an industrial city in the eastern Dnipro region, the country’s presidential office said.
In Balakliia, in the Kharkiv region, an 88-year-old man and a 78-year-old woman were rescued from the rubble of a house after Russian shelling, it said.
In the south, Russia attacked the city of Beryslav with drones, killing a 69-year-old man on a motorcycle.
There appears to be scant chance of an end to the war anytime soon.
Russian foreign minister Sergei Lavrov defied the United States and other Ukraine supporters at a UN meeting on Monday, ruling out any peace plan they support.
Mr Lavrov claimed Ukrainian forces have been “a complete failure” on the battlefield and are “incapable” of defeating Russia.
On Sunday, Moscow-installed officials in eastern Ukraine claimed shelling by Kyiv killed 27 people on the outskirts of Russian-occupied Donetsk.
The Ukrainian military, however, denied it had anything to do with the attack.
Kremlin spokesman Dmitry Peskov said Tuesday’s attacks should not be seen as Moscow’s response to the Donetsk strike.
He repeated Moscow’s claim that its forces do not strike civilian areas, although there is substantial evidence to the contrary.
Deaths of Ukrainian civilians have stirred international outrage over Russia’s invasion, and Ukrainian officials have pointed to the attacks in their efforts to secure further military aid from the country’s allies.
Ahead of tomorrow’s global conference on funding for Ukraine, I spoke with Ukrainian Defence Minister @Rustem_Umerov to coordinate the delivery of the UK’s record £2.5 billion support package.
The UK is committed to galvanising other nations to increase their support so we can…
— Rt Hon Grant Shapps MP (@grantshapps) January 22, 2024
Nato on Tuesday signed a 1.2-billion-US-dollar (£950-million) contract to make tens of thousands of artillery rounds to replenish the dwindling stocks of its member countries.
The contract will allow allies to backfill their arsenals and provide Ukraine with more ammunition.
Polish Prime Minister Donald Tusk on Monday became the latest foreign leader to visit Ukraine and announce a new aid package which includes a loan to buy larger weapons and a commitment to find ways to manufacture them together.
Ukraine’s allies have recently sought to reassure the country that they are committed to its long-term defence amid concerns that western support could be flagging.
UK Prime Minister Rishi Sunak and France’s new foreign minister also travelled to Kyiv in the new year.
But the United States, Ukraine’s main supplier, is currently unable to send Ukraine any ammunition or weapons.
While waiting for Congress to approve more money for Ukraine’s fight, the US is looking to its allies to bridge the gap.