At least six missiles hit Kharkiv in the first waves of Russia's attacks, Ukraine's National Police said on Sunday, injuring at least 22 people and hitting 12 apartment buildings, 13 residential houses and a kindergarten.
Earlier, Ukrainian officials said the injured in Kharkiv included two boys aged 14 and 16 and a security adviser for a team of German journalists.
Waves of Russian drones have hit residential buildings in Kharkiv, sparking fires, officials say. (AP PHOTO)
Closer to midnight, as part of a wider bombardment of Ukraine that also targeted Kyiv, several waves of Russian drones hit residential buildings in Kharkiv's centre, spouting fires, the mayor of Kharkiv, Ukraine's second-largest city, said.
"On the eve of the new year, the Russians want to intimidate our city, but we are not scared - we are unbreakable and invincible," the mayor, Ihor Terekhov, said.
The attacks came hours after what Moscow said was an "indiscriminate" Ukrainian air attack on the city of Belgorod, near Kharkiv and just north of Ukraine's border, that killed at least 22 people.
"Unfortunately, to our great grief, the number of those who have died in result of yesterday's strike at Belgorod has increased," said Vyacheslav Gladkov, the governor of the Belgorod region of which Belgorod city is the administrative centre.
The Belgorod region, which adjoins northern Ukraine, has like other Russian border zones suffered shelling and drone attacks all year that authorities have blamed on Ukraine, although none have previously been on such a scale.
Russia has vowed to retaliate after what it called Ukraine's "indiscriminate" attack on Belgorod. (AP PHOTO)
Three children were among those killed and 109 people have been wounded, Gladkov said in his statement on the Telegram messaging app.
Both sides deny targeting civilians in the war that Russia launched against its neighbour in February 2022.
According to the United Nations, more than 10,000 civilians have been killed in Ukraine and almost 60 people inside Russia.
The Russian defence ministry said on Saturday that Ukraine hit Belgorod with two missiles and several rockets, adding that most of the weapons were shot down, but that some debris fell on the city.
Gladkov said on Sunday the attack damaged 30 apartment buildings, as well as several houses and cars.
There has been no official comment from Kyiv.
Reuters has not been able to independently verify the Russian reports.
US President Joe Biden says he speaks to his Ukrainian counterpart Volodymyr Zelenskiy "regularly". (AP PHOTO)
The Ukrainian news outlet RBC-Ukraine quoted unidentified sources as saying Ukrainian forces had directed fire at military targets in Belgorod in response to the massive Russian bombardment of Ukrainian cities the previous day.
Russian newspaper Kommersant reported that Ukraine fired its air weapons from the Kharkiv region, just across the border.
Both sides have increased attacks in the final week of 2023, with Russia killing at least 31 civilians in its biggest air assault of the war on Ukraine on Friday.
United States President Joe Biden, asked if he would speak to Ukraine's President Volodymyr Zelenskiy after Russia's latest attacks in Ukraine, said: "I speak to him regularly."
