Ukrainian forces are fighting to retain control of Soledar in Ukraine's eastern Donetsk region, the regional governor said on Saturday, contradicting Russian claims that Moscow's forces had captured the small town.

Donetsk governor Pavlo Kyrylenko said the situation in the town was "difficult" and that Russian troops were advancing from various directions, adding that the Russians had sustained a large number of casualties, including members of the Wagner mercenary group.

"Soledar remains under control of our military, though there is street fighting and also fighting outside of the city because the enemy is trying to advance in several directions. The enemy is incurring huge losses," Kyrylenko said in a video posted on the Telegram app.

Reuters could not verify the battlefield accounts.

For days Soledar, a small salt-mining town, has been the focus of a Russian assault.

Kyrylenko's comments came after Russia said repeatedly that its forces had taken control of the town. Ukraine has repeatedly denied the takeover.

Kyrylenko said the front line was under constant shelling, with the Ukrainian military command working "to stabilize the situation, reduce losses and preserve the lives of our boys."

He said about 550 residents were still living in Soledar, which had a population of about 10,000 before the war.

Military experts have said Soledar itself is of little strategic importance but has gained political significance as part of Moscow's objective to capture the Donetsk region.