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".