"We can state for sure that this offensive has begun," Russian President Vladimir Putin said in Sochi.
"Ukrainian troops did not achieve their goals in any sector."
Ukrainian military analyst Oleksander Musiyenko, interviewed on Ukrainian NV Radio, said Ukraine was making gains but dismissed Russian reports of a major counter-offensive in south-central Zaporizhzhia region.
The counteroffensive is ultimately expected to involve thousands of Ukrainian troops trained and equipped by the West.
Deputy Defence Minister Hanna Maliar said only that battles were continuing for Velyka Novosilka and Russian troops were mounting "active defence" at Orikhiv.
Persons:
Putin, Zelenskiy, Vladimir Putin, Voldymyr Zelenskiy, Oleksander Musiyenko, Musiyenko, Ben Barry, They've, Barry, Hanna Maliar, Velyka Novosilka, Prystan, Oksana, Ukraine Denise Brown, Mark Trevelyan, Olena Harmash, Ron Popeski, Peter Graff, Diane Craft, Angus MacSwan, Nick Macfie, Andrew Heavens, Philippa Fletcher, Daniel Wallis
Organizations:
Press, State Emergency Service of, Ukrainian NV, West, United, Kyiv, International Institute for Strategic Studies, U.S, Bradley, Deputy, Reuters, United Nations, Kremlin, Thomson
Locations:
Russian, Ukraine, Zviahel, Zhytomyr region, State Emergency Service of Ukraine, Zhytomyr ., Russia, Ukrainian, KYIV, Moscow, Kyiv, U.S, Sochi, United States, Orikhiv, Crimea, Tokmak, Europe, Dnipro, Voronezh, Belgorod, Kursk