During a tour of European capitals, President Volodymyr Zelensky told heads of state and government at a summit in Brussels that the freedom of Europe depends on the freedom of Ukraine.
Russian forces have significantly stepped up their offensive in eastern Ukraine, seeking to breach defenses near Kreminna, Ukrainian governor Luhansk said.
The Russian embassy in London has warned of "military and political consequences" after Prime Minister Rishi Sunak said he was "not considering anything", including fighter jets for Ukraine.
Russia's Wagner Mercenary Group says it has stopped recruiting prisoners of war to fight in Ukraine.