Ukraine’s military claims to have broken through Russia’s first line of defence in the occupied Kherson region.
The reported push appears to form part of a long-awaited offensive being launched by Kyiv in an attempt to retake the country’s south.
It follows weeks of Ukrainian attacks aimed at cutting off Russian forces there from main supply routes.
Russia’s military has not commented on Ukraine’s claim, but one official said this was “yet another fake”.
“Ukrainian formations are suffering severe losses both in the south and in all other directions,” said Sergei Aksyonov, the Moscow-installed head of Crimea – Ukraine’s southern peninsula annexed by Russia in 2014.
The claims by both Ukraine and Russia have not been independently verified.
Russia has occupied large swathes of Ukraine’s Kherson region since its invasion began on 24 February.
Editing by Omotola Oguneye