Russia 'taken by surprise' as Ukraine advances in the east, say authorities

Kyiv (Ukraine): Ukrainian officials on Saturday claimed major gains in a counteroffensive against Russian forces in the country's northeast, saying Ukrainian troops had cut off vital supplies to 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 nearly seven-month war.

Ukrainian Foreign Ministry spokesman Oleh 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 Mechanized Battalion of Ukraine in front of what he said was a government building in Kupiansk, 73 kilometers (45 miles) north of Izyum.

The Security Service of Ukraine, known as the SBU, hours later posted a message which it said showed its forces in Kupiansk, further suggesting it had been seized by Ukrainian troops. The Ukrainian military didn't immediately confirm entering the town, a railway hub which Russia seized in February, when its mayor surrendered to avoid civilian casualties.

Later Saturday, 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.

Earlier Saturday, the British Defense Ministry told reporters it believed the Ukrainians had advanced as much as 50 kilometers (30 miles) south of Kharkiv, and described Russian forces around Izyum as increasingly isolated.

Russian forces were likely taken by surprise. The sector was only lightly held and Ukrainian units have captured or surrounded several towns, the British military said, adding that the loss of Kupiansk would greatly affect Russian supply lines in the area.