Russia said on Tuesday that its forces were tightening their encirclement of Ukrainian troops in the city of Pokrovsk, a transport and logistics hub they have been trying to capture for over a year.

With fighting raging in the streets of the ruined city, the Russian Defense Ministry said its soldiers had cleared 35 buildings of Ukrainian troops.

It said Russian forces were also squeezing surrounded Ukrainian troops near the town of Kupiansk in the Kharkiv region.

Reuters was unavailable to verify the battlefield reports. Ukraine has denied that its troops are encircled in either location.

DeepState, a Ukrainian project that maps the front line based on verified open source images, on Tuesday showed that Russian forces had pushed further into Pokrovsk and its environs, though it showed much of it still in grey, beyond firm control of either side.

Pokrovsk had a pre-war population of some 60,000, but most civilians fled long ago. Capturing it could give Moscow a platform to drive towards Kramatorsk and Sloviansk, the two biggest remaining Ukrainian-controlled cities in the Donetsk region which Russia wants to capture in its entirety.

Ukrainian President Volodymyr Zelenskyy acknowledged on Monday that Pokrovsk was under severe pressure, but his military said Russian troops were not in full control of any district.

Russian military blogger Rybar said on Tuesday that Moscow's control of the town was gradually expanding but "a complete clearing of the city is still far off."