As the war nears its third year, Moscow's troops have mounted heavy attacks and taken Avdiivka -- a key eastern town -- while Ukrainian troops are struggling with a lack of ammunition.

Army spokesman Dmytro Lykhoviy said late on Thursday that the area of Maryinka had become "another hot spot" following the fall of Avdiivka.

He said that "near the settlements of Novomykhailivka and Pobeda, the enemy with the support of aircraft tried to break through the defences of our troops 31 times".

These two villages are located southwest of Maryinka.

Russia on Thursday said its troops had captured Pobeda.

After the fall of Avdiivka, Russian troops are moving westwards, pushing Ukrainian forces further from the large separatist-held city of Donetsk.

President Volodymyr Zelensky this week described the situation on the front as "extremely difficult" due to delayed Western supplies of military aid.

Senior Ukrainian commander Oleksandr Tarnavsky, responsible for the sector, said on television that Russian troops had engaged Ukrainians in combat 43 times in Maryinka on Thursday.

"It is the Donetsk region, I mean the Avdiivka and Maryinka directions, that accounts for the absolute majority of air, artillery and kamikaze drone strikes," Tarnavsky said.

"I am grateful to our troops for their steadfastness in holding the defence line," he added.

Army spokesman Lykhoviy said the "situation is dynamic" and claimed some successes.

"Both in the Avdiivka and Maryinka directions our soldiers restored several positions" Thursday, and near Avdiivka "more than a dozen Russian occupiers surrendered or were captured by our military", he said.

Russia claimed to have captured Maryinka, west of Donetsk, in December, while Ukraine said its forces remained on the outskirts. Fighting was largely frozen until recent days.

Maryinka, which once had 10,000 residents, has been a focal point of fighting since 2014 and has been razed to the ground.