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.
Sharov said "small groups" of Ukrainian soldiers were trying daily to get into Kupiansk, a rail hub in the Kharkiv region.
But he insisted: "All areas are under the control of Russian forces."
Zelensky said in a video published on Friday that he had visited troops in the Kupiansk area, after Kyiv announced the recapture of several districts and two nearby localities.
His visit came shortly after Ukrainian forces announced a "breakthrough" in the area.
The Russian army launched a full-scale offensive in Ukraine in February 2022 and currently occupies 20 percent of the country, in the east and south.
