Kyiv (Ukraine) (AFP) - Russian officials in the southern border city of Belgorod offered to evacuate worried residents on Friday, an unprecedented announcement that follows waves of fatal Ukrainian attacks.

The Kremlin has tried to maintain a semblance of normalcy on the home front, but the recent strikes on Belgorod have brought the Ukraine conflict closer to home for Russians.

Governor Vyacheslav Gladkov's assurance that scared civilians can relocate represents the furthest-reaching measure taken by any major Russian city since Moscow ordered the invasion of Ukraine nearly two years ago.

"I see several appeals on social media where people write: We are scared, help us get to a safe place," governor Vyacheslav Gladkov said in a video message. 

"Of course we will! We have already moved several families," he added.

His offer came a day after overnight shelling wounded at least two people and knocked out glass from high-rise buildings, prompting widespread concern from residents.

The bout of shelling prompted city officials earlier Friday to urge residents to secure their windows with tape to prevent shattering from blast waves -- a measure widespread across Ukraine.

Ukrainian shelling in Belgorod less than a week ago killed 25 people -- the worst attack on Russian civilians since the conflict began.

Relocate 'as long as necessary'

Gladkov said residents would be transported to the towns of Stary Oskol and Gubkin, further from the border, where they would be housed in "comfortable conditions".

"You will stay there for as long as necessary," he added, but warned there would not be enough temporary accommodation to house everybody.

"I will appeal to my colleagues, the governors of other regions, to help us," he said.

His announcement came hours after Ukraine said it could not confirm that Russia had fired North Korean missiles into Ukraine after Washington accused Moscow of using weapons provided by Pyongyang.

The White House said late Thursday that Russia was using North Korean weapons and was also seeking missiles from its ally Iran, as it burns through stockpiles of key munitions.

US National Security Council spokesman John Kirby described the deliveries as a "significant and concerning escalation" but Ukraine said it had no independent evidence.

"So far, we have no information that such missiles have been used. The United States made a statement to that effect," Ukraine's air force spokesman Yuriy Ignat told state media.

"So experts will study the wreckage, and then we can say whether this is a fact or not. I can't confirm it yet," he added.

In the grinding war of attrition, Kyiv and Moscow have struggled to refill stockpiles of artillery shells, drones and long-range missiles.

The Pyongyang-supplied missiles with a range of around 900 kilometres (550 miles) were fired by Russia in two attacks within the past week, Kirby said.

He said at least one of the North Korean-supplied missiles had landed in an open field in the Zaporizhzhia region on December 30.

It is one of four regions that the Kremlin claimed to have annexed in September 2022 but still does not control entirely.

Moscow's forces then fired "multiple" ballistic missiles into Ukraine as part of a mass aerial attack on January 2, he added.

Russia rained down missiles on Ukraine's two largest cities, Kyiv and Kharkiv, on that date. Ukraine hit back at the Russian border city of Belgorod, forcing schools to close.

Ukraine drone barrage

Kirby said the North Korean missiles underscored the need for the US Congress to pass a package of major military aid for Ukraine, without which the pipeline of support will soon run dry, he added.

Air defences for Ukraine, which has come under a barrage of aerial attacks by Russia in recent days, were "absolutely" a priority, he said.

The United States said in October that North Korea had delivered more than 1,000 containers of military equipment and munitions to Russia, but it was the first time it had reported the use of such weapons.

Ukraine has substantially boosted its air defence systems compared to last winter, when systematic Russian strikes on energy infrastructure left millions in the cold and dark for extended periods.

Its air force said Friday that Russia had launched nearly 30 Iranian-designed attack drones overnight, but that 21 had been downed.

Russia's defence ministry said its forces had repelled a Ukrainian attack over Crimea, shooting down 36 drones over the peninsula annexed in 2014.