Three Ukraine-based Russian paramilitary groups say they have crossed into Russia and are now fighting government troops there.
The Freedom of Russia Legion (FRL) and Siberian Battalion (SB) posted videos purportedly showing their fighters in Russia's Belgorod and Kursk regions.
The FRL and an exiled Russian politician claimed two villages were now in control of "liberation forces".
Russia's defence ministry said the breakthrough attempts were thwarted.
It claimed more than 234 Ukrainian troops had been killed and several tanks had been destroyed.
Ukraine-based Russian armed groups claim raids into Russia
18 hours ago
By Jaroslav Lukiv,
BBC News
Share
Telegram/Freedom of Russia Legion An armed soldier in a video posted by the Freedom of Russia LegionTelegram/Freedom of Russia Legion
The Freedom of Russia Legion said Russia must be "freed from Putin's dictatorship"
Three Ukraine-based Russian paramilitary groups say they have crossed into Russia and are now fighting government troops there.
The Freedom of Russia Legion (FRL) and Siberian Battalion (SB) posted videos purportedly showing their fighters in Russia's Belgorod and Kursk regions.
The FRL and an exiled Russian politician claimed two villages were now in control of "liberation forces".
Russia's defence ministry said the breakthrough attempts were thwarted.
It claimed more than 234 Ukrainian troops had been killed and several tanks had been destroyed.
According to Belgorod's regional governor, Vyacheslav Gladkov, one member of Russia's territorial defence forces was killed and 10 civilians were injured.
These numbers have not yet been verified by the BBC.
Ukraine's military denied any involvement in Tuesday's cross-border raids. Andriy Yusov, a spokesman for the country's military intelligence, said the paramilitary groups were "independent organisations" of Russian nationals, and therefore operating "at home".
In a separate development, Russia said Ukraine had launched 25 drones on targets across Russia, but the attack was thwarted.
However, videos have emerged which appear to show several Russian oil facilities on fire.
