The head of the Russian administration installed in the occupied areas of the province, Vitaliy Ganchev, described the advance as a Ukrainian victory and called on civilians to flee.
Ukrainian officials released a series of images of troops entering towns previously controlled by Russia and hugging local residents who had been under Russian military occupation for six months.
The Ukrainian advance threatens to encircle thousands of Russian troops at Izium, the main Russian stronghold and logistics base in the northeastern sector of the front.
Oleksiy Arestovych, an adviser to the Ukrainian presidential office, in a video posted on YouTube, said the Russians in Izium were almost isolated.
Reuters was unable to immediately verify reports describing the situation at Izium. Ganchev, the Russian-installed regional official, included Izium among the towns where he said civilians should evacuate.
ADVANCE
Ukraine’s advance is by far the fastest in months, after a long period in which the war turned into relentless fighting along entrenched front lines.
Ukraine’s attack in the east came as a surprise just a week after it announced the start of a long-awaited counterattack to reclaim Russian-occupied territory hundreds of miles away. opposite end of the front at Kherson in the south.
Less information has been made public about this operation, but Kyiv also had some success there, cutting off supply routes to thousands of Russian soldiers isolated on the west bank of the Dnipro.
“We’re seeing success in Kherson now, we’re seeing some success in Kharkiv and so that’s very, very encouraging,” US Defense Secretary Lloyd Austin said at a news conference in Prague on Thursday.
Tens of thousands of people have been killed, millions driven from their homes and Russian forces have destroyed entire cities since launching what Moscow calls a “special military operation” to “disarm” Ukraine. Russia denies intentionally targeting civilians.