Kyiv said Sunday it had destroyed 21 of 49 Iranian-made drones fired after Russia vowed to retaliate for what it called a "terrorist attack" on a border city that left 24 dead.

The Ukrainian air force said the "Shahed" drones were particularly targeted at "the front line of defence, as well as at civilian, military and infrastructure facilities in the front-line territories".

Six guided missiles had also targeted the northeastern city of Kharkiv, Kyiv said in a statement on Telegram, without specifying whether they had hit their targets.

Oleg Sinegubov, the head of Kharkiv's military administration, said there had been 28 civilians wounded in the attack on the city, including two teenagers and a foreign citizen.

Residential buildings, offices and cafes were hit in the latest overnight attacks, said Kharkiv mayor Igor Terekhov.

"On the eve of the New Year, Russians want to intimidate our city, but we are not scared," he said.

The fresh Russian strikes came a day after the deadliest attack on civilians in Russia since the start of the conflict in February 2022.

The official death count has risen to 24 with 108 wounded in Belgorod -- just 30 kilometres (19 miles) from the Ukrainian border, which has been repeatedly struck by what Moscow says is indiscriminate shelling.

The two sides took turns to accuse each other of pummelling civilian areas of their shared frontier region over the weekend.

The governor of Belgorod region, Vyacheslav Gladkov, said Sunday that one person had been killed by Ukrainian shelling in a village close to the border.

'Blame Putin' 

Moscow said the Belgorod attack had included the use of controversial cluster munitions, and told an emergency meeting at the UN Security Council that Kyiv had targeted a sports centre, an ice rink and a university.

Russian envoy Vasily Nebenzya called it a "deliberate, indiscriminate attack against a civilian target".

Ukraine's allies countered that responsibility ultimately lay with Russian President Vladimir Putin for invading the neighbouring country nearly two years ago.

"If Russia wants someone to blame for the deaths of Russians in this war, it should start with President Putin," said British envoy to the UN Thomas Phipps.

Putin gave his traditional New Year's Eve address on Sunday, in which he praised Russia's soldiers on the front line and called for unity in the face of "difficult tasks".

"To all those who are on duty, on the front line of the fight for truth and justice," Putin said, "you are our heroes. Our hearts are with you. We are proud of you, we admire your courage."

Ukrainian President Volodymyr Zelensky is also set to give his New Year's address later.

January 1, day of mourning 

The Belgorod attack came a day after Ukraine said a barrage of Russian missile strikes on several cities, including the capital, had killed 39 people.

Schools, a maternity hospital, shopping arcades and blocks of flats were among the buildings hit in Friday's barrage, one of the most violent attacks since the start of the war.

Ukraine was still sifting through the rubble on Saturday when fresh strikes hit the regions of Kherson, Zaporizhzhia and Chernigiv, according to local authorities.

Three more people were killed by Russian strikes across Ukraine on Saturday, the officials said.

January 1 was to be declared a day of mourning in the capital Kyiv, where 19 people had been killed, city officials said.

Russia's army said it had "carried out 50 group strikes and one massive strike" on military facilities in Ukraine over the past week, adding that "all targets were hit".

The United Nations condemned the attacks and said they must stop "immediately".

Ukraine is urging Western allies to maintain military support.

"Next year will be a time of many decisions -- global decisions. And Ukraine needs to be able to influence them to be able to achieve its goals," Zelensky said in his evening address Saturday.

"We will fight for our influence, for justice for Ukraine, and I am grateful to all the leaders who help, who have been with us since February 24th and will be with us in 2024."

Britain announced it would send hundreds more air-defence missiles to Kyiv, after Prime Minister Rishi Sunak declared: "We must continue to stand with Ukraine -- for as long as it takes."

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)