Ukraine is sending reinforcements to a crucial hilltop town in eastern Donetsk, intensifying efforts to defend this strategic area.

The town's capture could significantly advance Russian forces into the region's industrial heartland.

Donetsk has faced the heaviest fighting since Russia's invasion in February 2022, with Ukrainian troops facing challenges in holding their ground against the better-equipped Russian military.

"Units of the 24th Mechanized Brigade have been redeployed to strengthen the defense of the Chasiv Yar sector," the grouping said in a statement late Thursday.

"The situation in and around the town is extremely difficult. The enemy is constantly organizing massive frontal assaults and also trying to bypass the settlement from the north and south," it added.

The unit had been deployed near the town of Toretsk, another frontline region where Russian forces have gained ground after a lull in fighting there, according to military bloggers.

Chasiv Yar, which had a pre-war population of around 12,000 people, sits above nearby civilian hubs of Kramatorsk and Kostiantynivka.

The Ukrainian military says it has been persistently targeted by Russian airstrikes, and recently released drone footage from the town shows rows of bombed-out and smoldering Soviet-era housing blocs.

Separately, authorities in the frontline town of Selydove further south in the Donetsk region said two people had been killed and three more were wounded in a Russian airstrike.

"The best thing to do is to evacuate and not endanger your own life and health," the regional governor said in a statement online announcing the attack.

The Kremlin said in late 2022 that it had annexed Donetsk, which has been partially controlled by Russian forces and Kremlin-backed separatists for around a decade.