Russia said Tuesday it controlled the key city of Kupiansk in northeast Ukraine, where Ukrainian forces recently claimed to have retaken territory.
"The city of Kupiansk is under the control of the Russian Sixth Army," Leonid Sharov, head of the Zapad military group, told state news agency TASS.
Diplomatic efforts to resolve the conflict have continued this week in Berlin, where Ukraine's President Volodymyr Zelenskyy hailed progress in talks with the US negotiators on Monday.
European leaders have put forward plans for a multinational force to guarantee peace.
Russia said it had captured Kupiansk in November but Ukraine later claimed it had retaken several areas of the city.
