The chief of the Russian private military group Wagner, Yevgeny Prigozhin, claimed Saturday that his forces have taken complete control of the eastern Ukrainian city of Bakhmut after months of brutal fighting.

"The operation to capture Bakhmut lasted 224 days," he said in a video posted to Telegram, seeking to claim a final victory for the city.

CNN could not independently verify Prigozhin's claim, but an initial response from the Ukrainian side disputed it.

Deputy Defense Minister Hanna Maliar, in a Telegram post less than an hour after the Russian mercenary's claim was published, admitted the situation in Bakhmut was "critical" but said Ukrainian troops were still "holding the defense" in the "Airplane" in a district on Bakhmut's western-most edge.

"As of now, our defenders control certain industrial and infrastructure facilities in the area and the private sector," she said.

While Russian forces have continued their slow street-by-street advance in the city itself for many months, over the last two weeks Ukrainian forces have managed to re-capture small pockets of territory held by Russian troops to the northwest and southwest of the city.

In confiremd, for Russia Bakhmut's capture would mark the country's first gain in months, but the city's symbolism always outweighed its strategic importance.

Russian forces, bolstered by members of the Wagner mercenary group, have taken heavy losses trying to capture the city.

There are no official casualty figures, but earlier this year a Nato source told CNN they estimated that for every Ukrainian soldier killed defending Bakhmut, Russia lost five.

This is a breaking news story. More to follow.