Ukrainian troops defending the northern city of Kharkiv have reached the state border with Russia, the regional governor said on Monday.
Governor Oleh Sinegubov made the claims on the Telegram messaging service.
The Ukrainian defence ministry has published a video purportedly showing a number of soldiers from a territorial defence brigade at an unspecified location on the frontier.
Sinegubov, said troops had restored a sign marking the border.
"We are proud of the soldiers... who restored the border sign on the state border!" he wrote on Telegram.
"We thank everyone who, risking their lives, liberates Ukraine from Russian invaders," he added.
The intensity of the shelling on the city of Kharkiv has "significantly reduced", he added.
Sinegubov said on Telegram that forces in the region are continuing to hold their ground and carry out successful counter-offensive actions.
It comes after he announced that Ukrainian troops had reached the border with Russia. That claim has not yet been verified.
He said that Russian forces are now focusing on maintaining their positions and preparing an offensive in the area of Izyum.
Ukrainian forces have been retaking territory in north-eastern areas in recent days, pushing the Russians out of artillery range of Kharkiv – which had endured weeks of bombardment. Russia has been continuing its offensive in the Donbas region further south.
Severodonetsk is the easternmost city still held by Ukraine, and its fall would grant the Kremlin de facto control of Lugansk, one of two regions -- along with Donetsk -- that comprise Donbas.
Russia's attempt to cross a river to encircle it has been repelled with heavy losses of equipment, according to Lugansk governor Sergiy Gaiday.
To further deter the attack, Russian-occupied railway bridges leading to Severodonetsk were blown up, the Ukrainian military said on Facebook late Sunday, posting a video of a huge explosion taken from above.
Gaiday said Monday that fighting in the region "continues almost around the clock".
For its part, Russia's defence ministry claimed it had struck four artillery munitions depots in neighbouring Donetsk.
Air strikes had also destroyed two missile-launching systems and radar, while 15 Ukrainian drones were downed around Donetsk and Lugansk, it added.
