Ukraine says its troops have caught occupying Russian troops "in a trap" in the shattered eastern city of Bakhmut, where its forces have been gaining ground as part of their counter offensive.
Russian accounts of the fighting said Moscow's forces have repelled or contained Ukrainian advances in the east and south.
More than 500 days into the invasion, Ukraine's counter offensive which began early last month has focused on capturing clusters of villages in the southeast and moving in on Russian forces holding Bakhmut.
Officials on Monday noted advances in both sectors.
"Bakhmut. The enemy is caught in a trap," General Oleksander Syrskyi, in charge of Ukraine's ground forces, said bluntly on the Telegram messaging app.
"The city is under the fire control of (our) defence forces ... the enemy is being pushed out of their positions."
In the south, General Oleksander Tarnavskyi said on Telegram Ukrainian forces were "on the move" and Russian forces had lost the equivalent of hundreds of men over 24 hours.
President Volodymyr Zelenskiy has said the counter offensive, boosted by supplies of sophisticated Western weaponry, is proceeding more slowly than Ukraine had hoped.
Military analysts say Kyiv wanted to point to at least a degree of success to leaders attending the NATO summit in Lithuania starting on Tuesday.
The Russian Defence Ministry said its forces had repelled Ukrainian attacks in three areas of Donetsk region, including Klishchiivka, the focus of clashes in recent days near Bakhmut.
The ministry also said Russian forces thwarted Ukrainian attacks in the south, including near the village of Rivnopil, which Ukrainian forces said they captured two weeks ago.
Ukraine's Deputy Defence Minister, Hanna Maliar, said on Telegram that over the past week Kyiv's troops had taken back 10.2 square kilometres of territory in the south and four in the east.
And the Ukrainian military said its troops had retaken 169 sq km on the southern front, and 24 around Bakhmut since the counteroffensive began.
Reuters could not verify the situation on the battlefield, and Russia has not acknowledged Ukrainian gains.
Moscow says fighting has been heavy since the counteroffensive began. Its forces still hold swathes of territory in eastern and southern Ukraine following its full-scale invasion on February 24, 2022.
Ukraine also reported new Russian attacks on civilian sites.
An attack on a humanitarian aid distribution point in the southeast killed seven people, emergency services said, and two people were killed by Russian shelling in the east.
Russia denies targeting civilian areas.
Earlier, Zelenskiy said the majority of NATO members stood together with his country and the Vilnius summit must confirm that Ukraine is a de facto member of the military alliance.
"The majority of the alliance stands firmly with us," Zelenskiy said in his nightly video message.
"When we applied for membership of NATO, we spoke frankly: de facto, Ukraine is already in the alliance. Our weapons are the weapons of the alliance. Our values are what the alliance believes in... Vilnius must confirm all this."
