The Russian Defense Ministry announced Monday that a humanitarian corridor has been from the Azovstal steel plant in Ukraine's port city of Mariupol.

"An agreement was reached with representatives of the Ukrainian military blocked at Azovstal in Mariupol to evacuate the wounded," the ministry said.

It added that a "regime of silence" was introduced for the duration of the evacuation and that the Ukrainian soldiers would be taken to a hospital in the nearby town of Novoazovsk.

There was no immediate confirmation from Ukrainian officials.

Hundreds of Ukrainian soldiers remained holed up in the underground tunnels of the huge Azovstal steel factory that has been besieged by Russian forces for weeks after Moscow claimed control of Mariupol. Ukraine's Azov Battalion, which has led the defense of Mariupol, has posted desperate videos from the plant, saying soldiers are dying from their wounds there.

Meanwhile, Ukraine has said its troops have regained control of territory on the Russian border near the country's second-largest city of Kharkiv, which has been under constant fire since Moscow's invasion began.

The Defense Ministry said in a statement on social media late Sunday that the Ukrainian troops of the 127th brigade in the Kharkiv region "drove out the Russians and claimed the state border."

In a video released with the statement, a clutch of Ukrainian soldiers in camouflage and holding weapons are gathered around a yellow-and-blue-painted border demarcation post and address President Volodymyr Zelenskyy.

The military has "reached the border with the Russian Federation – with the occupying country – we've done it; we're here," one of the soldiers says.

Ukraine presidential adviser Oleksiy Arestovich on Sunday told local television that Russian troops were being redeployed towards the Donbass region south of Kharkiv after withdrawing, following a Ukrainian counteroffensive.

Since failing to take the capital at the beginning of the invasion in late February, control of Donbass has become one of Moscow's primary objectives – but Western intelligence has predicted its campaign will stall amid heavy losses and fierce resistance.

"We thank everyone who, risking their lives, liberates Ukraine from Russian invaders," Kharkiv regional governor Oleg Synegubov said in a statement on social media.

"We still have a lot of work ahead of us," he added.

The Ukraine presidency said in a briefing Monday that Russia had continued strikes on the Luhansk region south of Kharkiv.

"Two people were killed and nine were wounded, including a child, as a result of shelling on a Severodonetsk hospital," it said, referring to a major urban hub.

Separately, police in the neighboring Donetsk region reported that six civilians were killed and 12 wounded in Russian shelling that hit 10 settlements in the area over the past 24 hours.

"Thirty-six civilian facilities were destroyed, including residential buildings, a mosque, a factory, a cafe," it said on Telegram.

In the western city of Lviv, city authorities said official infrastructure had been hit on May 13 by a cyberattack and that the Ukrainian SBU security services were working to limit the fallout.