Russian forces have taken control of a town where workers at the defunct Chernobyl nuclear plant live, the governor of the Kyiv region said on Saturday, and fighting was reported in the streets of the besieged southern port of Mariupol.
After more than four weeks of conflict, Russia has failed to seize any major Ukrainian city and on Friday Moscow signalled it was scaling back its military ambitions to focus on territory claimed by Russian-backed separatists in the east, reports Reuters.
However, intense fighting was reported in a number of places on Saturday, suggesting there would be no swift let-up in the conflict, which has killed thousands of people, sent some 3.7 million abroad and driven more than half of Ukraine's children from their homes, according to the United Nations.
Russian troops seized the town of Slavutych, which is close to the border with Belarus and is where workers at the Chernobyl plant live, the governor of Kyiv region, Oleksandr Pavlyuk, said.
He added that the soldiers had occupied the hospital and kidnapped the mayor. Reuters could not independently verify the reports.
Slavutych sits just outside the so-called exclusion zone around Chernobyl - which in 1986 was the site of the world's worst nuclear disaster - where Ukrainian staff have continued to work even after the plant itself was seized by Russian forces soon after the start of the Feb 24 invasion.
On the other side of the country, in Mariupol, Mayor Vadym Boichenko said the situation in the encircled city remained critical, with street fighting taking place in the centre.
The city has been devastated by weeks of Russian fire.
In an address on Saturday to Qatar's Doha Forum, Ukrainian President Volodymyr Zelensky compared the destruction of Mariupol to the destruction inflicted on the Syrian city of Aleppo by combined Syrian and Russian forces in the civil war.
"They are destroying our ports," Zelensky said, warning of dire consequence if his country - one of the world's major grains producers - could not export its foodstuffs. "The absence of exports from Ukraine will deal a blow to countries worldwide."
Speaking via video link, he also called on energy-producing countries to increase their output so that Russia cannot use its massive oil and gas wealth to "blackmail" other nations.