Russian President Vladimir Putin has claimed that Moscow's forces have made gains in Ukraine, including in the symbolic industrial hub of Avdiivka.

"Our troops are improving their position in almost all of this area, which is quite vast," he said in an interview on Russian television, an extract of which was posted on social media Sunday.

"This concerns the areas of Kupiansk, Zaporizhzhia and Avdiivka," Putin said, praising the army's "active defence strategy."

On Saturday, Kyiv reported "very heated" fighting around Avdiivka, saying Russian forces had "not stopped assaulting" it for days in their attempt to surround it.

Ukraine last week said Russia had stepped up assaults on the frontline city, which lies just 15 kilometers (9 miles) from Moscow-held Donetsk.

Avdiivka has been a symbol of Ukrainian resistance since 2014, after it briefly fell to Russian-backed separatists.

It has since marked the frontline and was regularly bombed even before the offensive began in February 2022.

It would be more of a symbolic victory than a strategic one if Russia does capture Avdiivka, which is built around a vast coking plant, given that the town has represented Ukrainian resistance to Russian assaults for so long.

Russian forces now control territory to the east, north and south of Avdiivka, gradually tightening the noose in a bid to push Ukrainian forces further from Donetsk.

Some 1,600 civilians are believed to be in the city, which had a pre-war population of 31,000.

'Encircle the city'

Ukrainian President Volodymyr Zelenskyy had said Kyiv was holding its ground in Avdiivka, but Moscow has previously claimed its positions had improved there.

On Saturday, the city's Ukrainian mayor, Vitaly Barabach, described the situation on the ground as "very tense," with the Russians attempting to "encircle the city" with "more and more troops."

According to Barabach, just over 1,600 civilians remain in Avdiivka, where evacuation is difficult due to the constant shelling.

On Sunday, Kyiv's army said Russian attacks had been "repelled" in the area.

"The enemy keeps trying to break through our defenses, but without success," it said.

Several analysts, using open source images of the assault on Avdiivka posted on social networks, have noted the Russians appear to suffering major losses of military materiel.

Russia's intensified assault on Avdiivka has come after four months of a Ukrainian counter-offensive, which has been slower than expected.

Putin on Sunday repeated that the counteroffensive had "totally failed."

"We know that in some combat zones, the enemy is preparing new offensive operations," he said.

"We see it, we know it. And as a consequence we are reacting."

Russian strikes have left four people dead and three wounded since Saturday in the eastern region of Kharkiv and Kherson, in the south, local authorities said.

In the Moscow-occupied zone in the Kherson region, three civilians were killed and another wounded on Saturday, according to local official Vladimir Saldo.