Both sides have conceded heavy losses in the battle for the salt mining outpost, with Moscow desperate to sell any win back home after repeated humiliations and Ukraine determined to hold -- and win back -- ground.

The Russian defence ministry announced it had "completed the liberation" of Soledar late the previous day and that the victory would pave the way for more "successful offensive operations" in the Donetsk region.

In a separate statement, it praised the "courageous and selfless" forces of mercenary group Wagner for storming Soledar.

The nod was an unusual recognition of the controversial force following talk of infighting and rivalry between Wagner and the official military.

The founder of Wagner, Yevgeny Prigozhin, insists that his force spearheaded the offensive for Soledar.

- 'Where should we go?' -

Kyiv dismissed Russia's announcement and said "severe fighting" was ongoing in Soledar, an industrial town with a pre-war population of around 10,000 now reduced to rubble.

Ukraine's Deputy Defence Minister Ganna Malyar said earlier that Russia had moved most of its forces around Donetsk to capture Soledar. "This is a difficult phase of the war," she said.

In Siversk, a town north of Soledar that could be next in line for the Russian advance, artillery echoed around the battered buildings dotted with a few remaining residents and Ukrainian military personnel braving light snow and a freezing wind.

Oleksandr Sirenko, who was chopping window frames and floors from destroyed flats into smaller pieces to store in the basement, said he did not want Kyiv's troops to retreat.

"You know, I've been afraid of many things in my life," he told AFP. "We only hope they don't retreat. We hope, we hope. We are afraid, but where should we go?"

- Stepping stone to Bakhmut? -

Capturing Soledar could improve the position of Russian forces as they push toward what has been their main target since October, the nearby transport crossroads of Bakhmut.

The Russian defence ministry said Friday that Soledar's capture "makes it possible to cut off supply routes of Ukrainian troops" there and surround them.

The US-based Institute for the Study of War said that Russian information operations have "overexaggerated" the importance of Soledar.

"But this small-scale victory is unlikely to presage an imminent encirclement of Bakhmut," it cautioned.

It said the fight for Soledar likely heavily taxed Russian battlefield resources, constraining its ability to quickly move on to the larger Bakhmut to the south.

- Ukraine intensifies call for arms -

Ukraine forces also have taken heavy losses in the battles of Soledar and Bakhmut and are calling on the country's allies to give it more weapons.

"To win this war, we need more military equipment, heavy equipment," the official, Andriy Yermak, said.

Foreign Minister Dmytro Kuleba said he had spoken with US Secretary of State Antony Blinken and "emphasised the need" for Ukraine to receive Western-type tanks.

"We also discussed further sanctions on Russia," Kuleba tweeted.

The calls came ahead of next week's meeting of the Ukraine Defense Contact Group, which coordinates arms supplies to Kyiv, at Ramstein Air Base in Germany.

Kyiv has stepped up pressure for western tanks, aircraft, and long-range munitions so far denied the country.

"This concern about the next level of escalation, for me, is some kind of protocol," Defence Minister Oleksiy Reznikov told the BBC on Friday, dismissing NATO fears about provoking Russia.

- German minister resigning? -

But on Friday German media reported that the country's defence minister and country host for the Contact Group meeting, Christine Lambrecht, has decided to step down.

Germany has been criticized for a reticence to provide Ukraine with significant amounts of advanced weapons, and most recently has resisted pressure to supply tanks.

German media said Lambrecht could step down in the coming days. She has also been faulted for a series of insensitive comments related to the war.

Contacted by AFP, a defence ministry spokesman declined comment on "rumours".

Meanwhile at the White House US President Joe Biden and Japanese Prime Minister Fumio Kishida reiterated their support for Ukraine.

"Japan's participation in the measures against Russia transformed the fight against Russia's aggression against Ukraine from a transatlantic one to a global one," Kishida said.