Ukrainian forces have continued to reclaim territory north of the country's second-largest city Kharkiv, UK officials have confirmed. 

Russia has reportedly withdrawn units from the region in an effort to "reorganise and replenish its forces following heavy losses", an intelligence update from the British Ministry of Defence confirmed. 

Having refocused resources predominantly on the Donbas region, Russia has left captured areas "vulnerable to the mobile, and highly motivated, Ukrainian counter-attacking force". 

The MOD statement reads: "Ukrainian forces are continuing to counter-attack to the north of Kharkiv, recapturing several towns and villages towards the Russian border.

"Despite Russia’s success in encircling Kharkiv in the initial stages of the conflict, it has reportedly withdrawn units from the region to reorganise and replenish its forces following heavy losses."

The update continued: "Once reconstituted, these forces will likely deploy to the eastern bank of the Siverskyi Donets River, forming a blocking force to protect the western flank of Russia’s main force concentration and main supply routes for operations in the vicinity of Izium.

"The withdrawal of Russian forces from the Kharkiv Oblast is a tacit recognition of Russia’s inability to capture key Ukrainian cities where they expected limited resistance from the population."

It comes after Ukraine stopped the flow of Russian natural gas through a hub that supplies European homes and industry.

The immediate practical impact of Wednesday’s gas cut-off was likely to be limited since much of the gas can be directed through another pipeline, gas analyst Zongqiang Luo at Rystad Energy said.

Preliminary flow data suggested that was already happening, though Russia’s state-owned giant Gazprom indicated some drop in supply.

It said it was sending gas supplies to Europe through Ukraine in the amount of 72 million cubic metres, apparently down 25 per cent on Wednesday compared to the day before.

A Russian commander has also suggested that Moscow's plans are broader than just capturing the Donbas region, despite Ukrainian counter-attacks. 

“The city of Kherson is Russia,” Kirill Stremousov, deputy head of the regional administration installed by Moscow, told Russia’s RIA Novosti news agency.

He said regional officials wanted to make Kherson a “proper region” of Russia.

Russian-installed authorities do not always speak for Moscow, but last month Mr Stremousov ruled out returning control of the Kherson region to Ukrainian authorities.

Kherson borders Crimea, which Russia annexed in 2014, and its capture was one of Russia’s most important successes in the war.