Ukraine’s President Volodymyr Zelensky says that Russian forces have seized 20% of his country’s territory, as Moscow’s invasion nears its 100th day.
Addressing lawmakers in Luxembourg, he added that the front line extended for more than 1 000km (621 miles).
“All combat-ready Russian military formations are involved in this aggression,” he told MPs via videolink.
Russian forces have been intensifying attacks on the city of Severodonetsk in the eastern Donbas region.
UK defence officials say Russia has seized most of the city and are making “steady local gains, enabled by a heavy concentration of artillery”.
Severodonetsk is the easternmost city under Ukrainian control and regional governor Serhiy Haidai said Russia was trying to break through defences in the city “from all directions”.
However he said Ukrainian troops were carrying out counter-attacks, “pushing back the enemy on some streets and taking several prisoners”.
Intense street-to-street fighting in the city had hampered evacuations, he said, describing such efforts as “extremely dangerous”.
In a video address late on Thursday evening, Zelensky said the situation in Donbas had not changed significantly that day but that Ukrainians had experienced “some success” in battles in Severodonetsk.
Some 15 000 civilians remain trapped in the city, with many of them taking shelter at the massive Azot chemical plant.
On Wednesday, Zelensky accused Russia of “madness” after its troops allegedly targeted the site during an artillery barrage.
Further south, the mayor of the occupied city of Mariupol has accused Russian forces of executing civil servants who have refused to collaborate with the new Moscow-backed city authority.
Vadym Boychenko, who was evacuated from Mariupol before it fell, said dozens of residents were being held at the Olenivka Prison and that he had received reports of locals being tortured by occupying forces. The BBC cannot verify these allegations.
Last week an adviser to Boychenko told CNN that at least 22 000 people had been killed during Russia’s siege and bombardment of the city.
In the north-east, Russian shelling killed a woman and injured a man in Kharkiv, regional officials said.
And in western Ukraine five civilians were hurt in missile strikes on Lviv, regional head Maksym Kozytskyi said. (BBC)