A day after Ukraine bombarded the Russian border city of Belgorod, Moscow launched retaliatory strikes on Kyiv targeting the military sites and 'foreign mercenaries' in Kharkiv, CNN reported.
At least three people were killed and 28 others were injured after Kharkiv was struck with waves of missiles and drones, Ukrainian officials said.
Earlier, Ukraine's bombardment of Belgorod city killed at least 24 people, according to CNN.
The head of Ukraine's regional military administration, Oleh Syniehubov, said in a post on Telegram that rescuers had retrieved the bodies of two men and a woman from a house damaged by Russian attacks on the village of Borova, in the Kharkiv region.
Meanwhile, Russian President Vladimir Putin gave a pared-back New Year's Eve message, praising Russian soldiers but not directly mentioning Ukraine.
In the reprisal attacks, several missiles struck the city of Kharkiv with two children among those injured, the Ukrainian military said.
Residential buildings, hotels and medical facilities were also damaged in the strikes, while Ukraine added that Russia kept up its attacks across other areas of the country overnight including the Kherson, Mykolaiv and Zaporizhzhia regions, according to CNN.
According to a statement from Russia's ministry of defence, its strikes targeted "decision-making centers and military installations," including a hotel housing military commanders and "foreign mercenaries."
The former Kharkiv Palace hotel and the headquarters of the Ukrainian Security Service for the Kharkiv region were hit, the statement read.
It added that a control centre used by the Ukrainian army in the village of Zalestsy in Khmelnytskyi region was targeted and fuel depots in Kharkiv and Zaporizhzhia were destroyed.
Two HIMARS multiple-launch rocket systems were also destroyed, CNN reported citing the statement.
In a separate attack on the southern city of Kherson on Sunday, a teenage boy was killed and three people were left injured, according to local officials.
A nine-year-old child sustained a head injury and is fighting for his life, the official said.
Russia said that the strikes overnight were in response to the deadly Ukrainian strike on the city of Belgorod on Saturday -- an attack it blamed on Ukraine and condemned by Russia's MOD as a "terror attack."
At least 24 people, including three children, were killed and 107 others wounded in Belgorod, in one of the single deadliest attacks on Russian civilians since the war began.
Among those injured, 25 are in serious condition, including six children. There has been no official comment from Ukraine.
The Russian defence ministry had vowed the bombardment "would not go unpunished."
In his speech emphasising national unity, Putin called his military "heroes."
"We have proven more than once that we can solve the most difficult problems and will never back down".
"In the past year we have worked hard and accomplished a lot. We were proud of our common achievements, rejoiced at our successes and were firm in defending national interests," Putin said.
The address will be shown before midnight local time in all 11 time zones in Russia. Last year, he spoke from the headquarters of Russia's Southern Military District in Rostov-on-Don, flanked by members of the military.
The final weeks of 2023 have seen an increased number of attacks from both sides.
Earlier on Friday, Russia launched its biggest air attack on Ukraine since the beginning of its full-scale invasion.
An unprecedented number of drones and missiles were fired at targets across the country, killing at least 47 people, CNN reported.
