Ukraine has said it was dispatching reinforcements to an embattled strategic hilltop town in the eastern Donetsk region, a vital flashpoint whose capture could accelerate Russian advances deeper in the industrial territory.

Donetsk has borne the brunt of fighting since Russian forces invaded in February 2022, and Ukrainian forces are struggling to hold the line there against better-resourced Russian forces.

"Units of the 24th Mechanized Brigade have been redeployed to strengthen the defence 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 organising 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 air strikes, and recently released drone footage from the town shows rows of bombed-out and smouldering Soviet-era housing blocs.

Ukrainian police meanwhile said five people had been killed and another 11 wounded in Russian attacks on the Donetsk region throughout the day.

"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.

Further west, the governor of the Zaporizhzhia region, said a 32-year-old civilian had been killed and two other were wounded by Russian fire near the village of Vozdvyzhivka.

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