MOSCOW - Russia said on Wednesday that its forces were advancing north inside Pokrovsk in a drive to take full control of the Ukrainian city, but the Ukrainian army said its units were battling hard to try to stop the Russians from gaining new ground.

Ukraine has acknowledged that its troops face a difficult position in the strategic eastern city, once an important transport and logistics hub for the Ukrainian army, which Russia has been trying to capture for more than a year.

Russia sees the city as the gateway to its capture of the remaining 10%, or 5,000 square km (1,930 square miles) of Ukraine's eastern industrial Donbas region, one of its key aims in the almost four-year-old war.

The Russian defence ministry said two assault groups were destroying Ukrainian troops that were surrounded in several districts of the city and continuing an offensive pushing north through it. Russian forces were clearing Ukrainian troops from settlements on Pokrovsk's southeastern flank and had repelled Ukrainian attempts to break out of encirclement.

The Ukrainian military denied that its troops were surrounded in Pokrovsk. It said they were trying to stop Russian soldiers from digging in while seeking to secure and protect logistics routes in the wider area.

"Measures are being taken to block the enemy, which is attempting to infiltrate and accumulate in the city of Pokrovsk," the Ukrainian General Staff said in a statement.

"Active countermeasures are being taken against attempts by enemy infantry groups to gain a foothold."

Ukrainian President Volodymyr Zelenskiy said on Monday the area around Pokrovsk remained under severe pressure but that up to 300 Russian servicemen still in the city had made no gains in the past day and there were just 60 in another city, Kupiansk.

The Russian Defence Ministry said on Wednesday that either Zelenskiy had no grasp of what was happening or he was deliberately trying to conceal the parlous situation for Kyiv's forces.

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