A third wave of Russian forces is attacking the eastern Ukrainian town of Avdiivka and systematically shelling the centre of the industrial hub, its Ukrainian head said Friday.

The nearly-encircled town near the Russian-held regional stronghold of Donetsk has faced a fierce onslaught for more than a month.

"The third wave (of assaults) began. They are attacking from all directions, from the flanks of the south and north, as they did before. They are attacking the industrial zone," Vitaly Barabash, the head of the town, said.

Avdiivka has been on the front line since 2014 and is part of the Donetsk region, which the Kremlin has claimed to have annexed along with three other regions.

"They are attacking from all sides, using a lot of infantry. Machinery went to the industrial zone, because the asphalt surface allows them to do so," Barabash told state media.

He said Russian forces were targeting Avdiivka with guided air bombs and cluster munitions resulting in between 30 and 40 "massive" strikes each day.

Barabash said 1,350 residents were remaining in the town that had a pre-war population of around 30,000 people, and that 102 people had been evacuated over the last week.

Under fire since 2014, the town has been largely destroyed by shelling, but has become a symbol of Ukrainian resistance.