Russian forces are stepping up their use of heavy artillery and air strikes in the devastated eastern Ukrainian city of Bakhmut, the commander of Ukraine's ground forces said on Tuesday.
Fighting in and around Bakhmut has for months been the epicenter of the war in Ukraine, Reuters said.
"Currently, the enemy is increasing the activity of heavy artillery and the number of air strikes, turning the city into ruins," General Oleksandr Syrskyi said in a statement.
He said Russia, which launched its full-scale invasion of Ukraine in February last year, remained committed to taking Bakhmut "at any cost" but was suffering significant losses in the battle for the city.
Reuters could not confirm the battlefield situation. Russia says Ukrainian forces have also suffered heavy losses in Bakhmut.
The city, which had a pre-war population of about 70,000, has been Russia's main target in a winter offensive that has yielded scant gains despite infantry ground combat of an intensity unseen in Europe since World War Two.
Bakhmut's capture could provide a stepping stone for Russia to advance on two bigger cities it has long coveted in the Donetsk region of eastern Ukraine: Kramatorsk and Sloviansk.
The head of the Wagner mercenary group, which has spearheaded Russia's attempt to take Bakhmut, said this month that its fighters controlled more than 80% of the city.
Ukraine denied this, saying it still controlled considerably more than 20% of the city. The Ukrainian military is widely expected to mount a counteroffensive in coming weeks or months aimed at recapturing Russian-held territory.