Russian troops destroyed or captured several Ukrainian positions near the eastern city of Pokrovsk, Kyiv's military said on Wednesday, as Moscow bears down on the strategic logistics hub that is home to a unique Ukrainian coking mine.

After months of accelerating advances toward Pokrovsk, Moscow's forces are now as close as three kilometres from the southern outskirts of the city, according to Ukraine's DeepState, which maps the front lines using open sources.

"As a result of prolonged clashes, two of our positions were destroyed, one was lost. Currently, measures are being taken to restore positions," Nazar Voloshyn, Ukraine's military spokesperson for the eastern front, said in televised comments.

The fall of Pokrovsk, an important logistics centre for the Ukrainian military, would amount to the biggest military setback for Kyiv in months. The city also hosts a mine which is Ukraine's only domestic coking coal supplier for its once-giant steel industry.

Ukraine's top commander, Oleksandr Syrskyi, said he had visited a marine unit in the Pokrovsk sector and noted the conditions servicemen faced against "an enemy superior, primarily, in terms of manpower."

"Unconventional decisions must be made to enhance the resilience of our defence and ensure more effective destruction of the occupiers," he wrote on Facebook, without mentioning when the visit took place.

"The battles are exceptionally fierce. The Russian occupiers are throwing all available forces forward, attempting to break through our troops' defences."

Months of fierce fighting

Pokrovsk, situated about 18 kilometres from the boundary of Ukraine's Donetsk and Dnipropetrovsk regions, has for months been the area of the fiercest battles in Russia's 33-month-old full-scale invasion of Ukraine.

In October and November, the Russian military advanced toward the city at its fastest rate since the early months of the war, analysts said. Ukraine says Russia has been sustaining some of its heaviest losses of the war to date.

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Both Ukraine and Russia have their eye on the growing prospect of a push for peace talks, with U.S. president-elect Donald Trump preparing to enter office on Jan. 20, having called for an immediate ceasefire and a swift end to the war.

Kyiv has urged its allies to get it into the strongest possible position on the battlefield before any talks do happen.

Russia, which Ukraine says has over 70,000 troops on the Pokrovsk front, has rapidly advanced toward Shevchenko, a village to Pokrovsk's south, in recent weeks.

Its forces are trying to gain a foothold in the village and are sending in reconnaissance and sabotage groups, spokesperson Voloshyn said. Ukraine is holding them back for now, he added.

The coal mine, which was still operating as of Dec. 6, lies 10 kilometres west of Pokrovsk, on the far side from where Russian troops have been advancing.