The office of Ukraine’s President released video on Thursday showing what it says are destroyed or disabled Russian military vehicles outside the city of Kharkiv, as well as what it said was the body of a Russian soldier.
Kharkiv lies in the east of Ukraine, close to the border with neighbouring Russia.
Ukrainian forces battled invaders on three sides after Moscow mounted an assault by land, sea and air in the biggest attack on a European state since World War Two, prompting tens of thousands of people to flee their homes.
After Russian President Vladimir Putin declared war in a pre-dawn televised address, explosions and gunfire were heard throughout the morning in Kyiv, a city of 3 million people.
An adviser to the office of Ukraine President Volodymyr Zelenskiy said Russian forces had captured the Chernobyl former nuclear power plant, just 90 km north of the capital, and Hostomel airport in the Kyiv region, where paratroopers had earlier been landed.
Heavy exchanges of fire were also taking place in the regions of Sumy and Kharkiv in the northeast and Kherson and Odessa, home to a populous city and Ukraine’s most important seaport, in the south.