Emergency crews searched for survivors in the rubble of a mall in central Ukraine that was pounded by Russian missiles, while the ambassador to Moscow of the separatist Luhansk People's Republic said street battles had broken out in Lysychansk.
More than 1,000 people were inside when two Russian missiles slammed into the shopping mall in Kremenchuk, Poltava, Ukrainian President Volodymyr Zelenskiy said.
At least 18 people were killed and 25 hospitalised, while about 36 were missing, said Dmytro Lunin, governor of Poltava.
Family members of the missing lined up at a hotel across the street where rescue workers set up a base after Monday's strike on the busy mall in Kremenchuk, in the region of Poltava, southeast of Kyiv.
Leaders of the Group of Seven (G7) major democracies, at a summit in Germany, said the attack was "abominable".
"Russian President Putin and those responsible will be held to account," they said in a joint statement
Russian troops and their Luhansk Republic allies are advancing into Lysychansk and street battles have erupted, said the ambassador to Moscow of the Luhansk People's Republic, recognised only by Russia.
Reuters could not confirm Russian reports that Moscow's troops had already entered the city.
Ukrainian forces still controlled Lysychansk, but its loss was possible as Russia poured resources into the fight, Luhansk Governor Gaidai said.
Russia shelled Kharkiv, hitting apartment buildings and a primary school, the regional governor said. The shelling killed five people and wounded 22 including children.
The White House said Russia had defaulted on its foreign sovereign bonds for the first time in a century - an assertion Moscow rejected.
Ukrainian President Zelenskiy asked for more arms in a video address to the G7 leaders.
Zelenskiy was focused on securing an "advantageous position" in months rather than years, U.S. National Security Adviser Sullivan said. A European official said the Ukrainian leader wanted the war to be over by winter.
U.S. President Biden raised the tariff rate on certain Russian imports to 35 per cent as a result of suspending Russia's "most favoured nation" trading status.
