Ukrainian troops continued a counteroffensive on the front line around two cities in the east of the country on Friday, President Volodymyr Zelensky said, quoted by "Reuters".
He said Russian forces had suffered heavy losses.
Russia said its forces had captured two new villages in their slow advance through eastern and southern Ukraine. The Defense Ministry, however, did not mention the Ukrainian offensive near the towns of Pokrovsk and Dobropol.
In his nighttime video address, Zelensky said the counteroffensive had disrupted Russian plans for their long-standing goal of capturing the Pokrovsk logistics center.
"One of the most important directions of the Russian offensive was located there, but they failed to launch a full-fledged offensive. Our military is destroying their forces," he said.
"The Russians suffered significant losses and the "exchange fund" "for our country, it has significantly increased - more and more Russian prisoners are being taken every day," Zelensky also noted.
Ukraine's Supreme Commander-in-Chief Oleksandr Syrsky wrote on Telegram that his forces had advanced three to seven kilometers through Russian defense lines.
In his video address, Zelensky also said that Ukrainian forces were holding their positions around Kupyansk, an area in the northeastern part of Ukraine's Kharkiv region that has been under Russian attacks for months.
On Thursday, Zelensky said that Ukrainian forces had recaptured seven settlements and 160 square kilometers around Pokrovsk and Dobropol since the start of the operation. Another nine settlements had been "cleared" by enemy forces.
The Donetsk region, which is only partially occupied by Russia but which Moscow wants Kiev to abandon before a peace deal is reached, remains the scene of the most intense fighting.
The Russian Defense Ministry said its forces had captured two more towns - Muravka, southwest of Pokrovsk, and Novoivanovka, further southwest in Zaporizhia Oblast.
The General Staff of the Ukrainian Armed Forces cited Muravka as one of several towns where its forces had stopped 87 attacks near Pokrovsk.
A senior official in the Russian-appointed administration in the Moscow-controlled areas of Donetsk Oblast said Russian forces now have effective control over all roads and other logistical facilities around Pokrovsk.