The head of Russia’s Wagner mercenary group acknowledged on Wednesday that fighting for the Ukrainian city of Bakhmut had inflicted severe damage on his own forces as well as the Ukrainian side.

Bakhmut, a small eastern city that has for months been the target of a Russian offensive, has seen intense fighting and destruction in what has become the longest, bloodiest battle of the war.

“The battle for Bakhmut today has already practically destroyed the Ukrainian army, and unfortunately, it has also badly damaged the Wagner Private Military Company,” Wagner chief Yevgeny Prigozhin said in an audio message.

Russian officials say their forces are still capturing ground in street-by-street fighting inside Bakhmut, but have so far failed to encircle it and force the Ukrainians to withdraw, as had seemed likely weeks ago.

British military intelligence said on Wednesday the Ukrainians had successfully pushed the Russians back from one of the city’s main supply routes.