The situation in the city of Bakhmut, on the eastern front line, is becoming "more and more difficult", Ukraine's President Volodymyr Zelensky has said.
Russian forces have been trying to take the city for over six months.
"The enemy is constantly destroying everything that can be used to protect our positions", Mr Zelensky stated.
The Ukrainian leader's remarks came as US Treasury Secretary Janet Yellen warned China against arming Russia during a visit to Kyiv on Monday.
Some of the fiercest fighting since Russia invaded Ukraine just over a year ago has taken place in Bakhmut, in Ukraine's Donetsk region, part of which is under the control of Russia and its proxy forces.
Recently efforts by Russian forces to capture the industrial city have intensified, with its troops gaining ground. Footage carried by the Russian RIA state news agency showed Su-25 fighter jets roaring over Bakhmut. sexxygame666