The government has asked power companies to top up their liquefied natural gas (LNG) reserves and share energy resources, a person familiar with the contingency plan said, as civilian deaths in Ukraine push Tokyo to halt Russian fuel imports.

Utilities are scrambling for already stretched energy sources as resource-poor Japan joins the West in punishing Russia, a major oil and gas producer — a search made harder on Friday when Prime Minister Fumio Kishida announced a ban on Russian coal and other sanctions.

Kishida, who faces national elections in July, is seeking to balance energy security for the world's third-biggest economy against growing pressure on the Group of Seven industrial powers for harsher sanctions against Russia as allegations of atrocities in Ukraine spread.