Ukraine said Wednesday that Russian forces had ratcheted up attacks on the nearly-encircled industrial town of Avdiivka in the eastern Donetsk region, a recent flashpoint of Moscow's invasion.

Avdiivka -- which was once home to around 30,000 people -- 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.

Russia launched a renewed bid to capture the war-battered town last month and analysts suggest Moscow's forces have made incremental gains.

"The enemy of the last day has significantly increased its activity. It is using armoured vehicles," Oleksandr Tarnavsky, the Ukrainian commander responsible for the territory, said.

He said Russian forces had carried out nearly 20 airstrikes, launched four missiles and thrown 56 assault waves at his forces, and fired more than 1,000 artillery rounds.

He claimed that Ukrainian forces were "firmly holding the line along the Avdiivka front," which AFP was unable to independently verify.

Neither side has made significant breakthroughs on the battlefield for weeks, as Moscow's invasion drags on for a 22nd month.