Russian troops have broken through the defences of Ukrainian forces in part of the Luhansk region, the Russian Defence Ministry said early on Wednesday.
"During the offensive ... the Ukrainian troops randomly retreated to a distance of up to three kilometres (1.9 miles)from the previously occupied lines," the ministry said on the Telegram messaging app.
"Even the more fortified second line of defence of the enemy could not hold the breakthrough of the Russian military."
Reuters was not able to independently verify the battlefield report.
The ministry did not specify in which part of the Luhansk region the offensive took place.
Ukraine's military has been reporting increasingly heavy Russian shelling along the frontline, with officials calling the situation difficult, but also saying that its army has been able to repel many Russian attacks. Ukraine has urged allies to speed up the pace of military aid.
Russia now holds swathes of the southern regions of Kherson and Zaporizhzhia, including its nuclear plant, nearly all of Luhansk and over half of Donetsk, including the regional capital.
