Ukraine’s military said its troops were locked in combat with Russian forces around the administration building of Bakhmut on Monday, and it poured scorn on Russian claims that mercenary fighters had captured the eastern city after months of warfare.

A Ukrainian spokesman said the Russians had raised a victory flag not over the building but over “some kind of toilet”.

In Moscow, the Kremlin accused Ukraine of being behind a bomb blast at a cafe in St Petersburg on Sunday that killed prominent Russian prowar blogger Vladlen Tatarsky. Russia said it had arrested a woman suspected of blowing up the blogger.

The battle for Bakhmut has been one of the bloodiest of the conflict, now in its second year, with many casualties on both sides and much of the eastern city destroyed by bombardments.

The head of the Wagner mercenary force, which has spearheaded the Kremlin’s campaign to encircle and capture Bakhmut, said on Sunday his troops had raised a Russian flag on the administrative building in the city centre.

Yevgeny Prigozhin acknowledged that Ukrainian troops were still holding some positions. But he said in a video posted on Telegram: “From a legal point of view, Bakhmut has been taken. The enemy is concentrated in the western parts.” Prigozhin has previously made claims that were premature.

The Ukrainian military said on Monday, however, that fighting was still going on in Bakhmut as well as in several other towns. Serhiy Cherevatiy, spokesperson for the eastern military command, said the Russian claim to have captured the city was false.

Clashes were taking place around the city council building, he said.

“Bakhmut is Ukrainian and they have not captured anything and are very far from doing that, to put it mildly,” he told Reuters.

“They raised the flag over some kind of toilet. They attached it to the side of who knows what, hung their rag and said they had captured the city. Well good, let them think they’ve taken it,” Cherevatyi said over telephone.

Ukrainian President Volodymyr Zelensky, in his Sunday night video address, thanked the soldiers fighting in Bakhmut, Avdiivka and Maryinka.

“Especially Bakhmut. It is especially hot there,” he said.