The head of the Wagner mercenary force, which is spearheading the Russian attack on Bakhmut, said his forces had advanced up to 400 meters. "We're pushing Bakhmut all the way to the end," he said in an audio recording on his Telegram channel.

While Russia boosted its forces in the city, attacked the suburbs to the north and engaged in fierce fighting in the southern suburbs, Ukraine's forces advanced 500 meters in the north and in some areas in the south by one kilometre, Deputy Defence Minister Hanna Maliar said on her Telegram channel.

"The defence of Bakhmut and its outskirts is meeting its military objectives," she said. "As of now, we control the southwestern part of Bakhmut."

She said that Russia had attacked Bakhmut all day having "significantly strengthened" its grouping in Bakhmut by bringing most of its reserves there.

"All the attacks were repelled by our defenders," she added.

Kyiv has for days been hailing battlefield successes around Bakhmut that could eventually trap Wagner's forces inside the city.

Prigozhin, who said a week ago that his forces' flanks were under pressure near Bakhmut, said they continued to be eroded. "Most likely, holding Bakhmut is part of the (Ukrainian) counteroffensive plan," he added.

Moscow sees Bakhmut, a city of about 70,000 before Russia's full-scale invasion nearly 15 months ago, as a stepping stone toward capturing the rest of the eastern Donbas region.