RUSSIA’S defence ministry said it is pulling back forces from two areas in Ukraine’s Kharkiv region where a Ukrainian counteroffensive has made significant advances in the past week.

Defence spokesman Igor Konashenkov said the troops would be regrouped from the Balakliya and Izyum areas to the Donetsk region. Izyum was a major base for Russian forces in the Kharkiv region.

Konashenkov said the move is ­being made “in order to achieve the stated goals of the special military operation to liberate Donbas,” one of the eastern Ukraine regions that ­Russia has declared sovereign.

The claim of a pullback to ­concentrate on Donetsk is similar to the justification Russia gave for ­pulling back its forces from the Kyiv region earlier this year.

READ MORE: 'We were geared up and we went to ­defend Kyiv': A Ukrainian soldier's story

Earlier yesterday, Ukrainian ­officials claimed major gains in a counteroffensive against Russian forces in the country’s north-east, ­saying vital supplies to the invaders had been cut off from the front-line hotspot.

The reports followed several days of apparent advances by Ukraine south of Kharkiv, the country’s second-largest city, in what could become the ­biggest battlefield success for Ukrainian forces since they thwarted a Russian attempt to seize the capital of Kyiv at the start of the war nearly seven months ago.

Ukrainian foreign ministry spokesperson Oleg Nikolenko suggested the Ukrainian troops had retaken ­Kupiansk, a town along the main ­supply route to Izyum, long a focus on the Russian front line and the site of heavy artillery and other fighting.

Nikolenko tweeted a photo ­showing soldiers of the 92nd ­Separate ­Mechanised Battalion of Ukraine in front of what he said was a ­government building in Kupiansk, 45 miles north of Izyum.

Hours later, the Security Service of Ukraine (SBU) posted a message which it said showed its forces in ­Kupiansk, further suggesting this ­territory has been seized by ­Ukrainian troops.

The Ukrainian military did not ­immediately confirm entering the town, a railway hub which ­Russia seized in February, when its ­mayor surrendered to avoid civilian ­casualties.

Later yesterday, videos on ­social media began to circulate also ­appearing to show Ukrainian forces on the rural outskirts of Izyum at a roadside checkpoint. A large statue bearing the city’s name could be seen in the footage. Ukrainian forces did not acknowledge holding the city.

Our foreign editor David Pratt said: “If fully confirmed, this is one of the most incredible turnarounds in the war to date.”

Earlier, the UK Ministry of ­Defence told reporters it believed the ­Ukrainians had advanced as much as 30 miles south of Kharkiv, and ­described Russian forces around ­Izyum as “increasingly isolated”.

The MoD added: “Russian forces were likely taken by surprise. The ­sector was only lightly held and Ukrainian units have captured or ­surrounded several towns.” It ­added that the loss of Kupiansk would ­greatly affect Russian supply lines in the area.

The Institute for the Study of War, a Washington-based think tank, likewise referenced sweeping Ukrainian gains, estimating that Kyiv has seized around 965 square miles in its north-eastern breakthrough.

The institute said it appeared that “disorganised Russian forces [were] caught in the rapid Ukrainian ­advance”.

They cited social media images of apparent Russian prisoners seized in the advance around Izyum and ­surrounding towns.

The same report said ­Ukrainian forces “may collapse Russian ­positions around Izyum if they sever Russian ground lines of ­communication” north and south of the town.

Moscow did not immediately ­acknowledge or comment on the claims by Ukraine and its Western allies.

Vladislav Sokolov, the head of the Russian-appointed local ­administration, said on social media that authorities in Izyum have ­started evacuating residents to Russia.

The fighting in eastern Ukraine comes amid an ongoing ­offensive around Kherson in the south. ­Analysts suggest Russia may have ­taken soldiers from the east to ­reinforce around Kherson, offering the Ukrainians the opportunity to strike a weakened front line.

Ukrainian defence minister Oleksii Reznikov told the television channel Ukraina that the Russians had no food or fuel for their troops in the area as Kyiv had cut off their supply lines.

“It will be like an avalanche,” he said, predicting a Russian fallback. “One line of defence will shake and it will fall.”

Ukrainian President Volodymyr Zelenskyy said in a nightly video ­address on Friday that Ukrainian troops had reclaimed more than 30 settlements in the Kharkiv region since the start of the ­counteroffensive.

“We are gradually taking control over more settlements, returning the Ukrainian flag and protection for our people,” Zelenskyy said.

He spoke after the Ukrainian ­governor of Kharkiv reported that the national flag had been raised over Balakliia, a town recaptured by Ukrainian troops on Thursday ­following six months of Russian occupation.