Kyiv Mayor Vitaliy Klitschko said the city's metro system is back in operation and all residents have been reconnected to water supplies, a day after the latest wave of Russian airstrikes on key infrastructure.

Ukrainian officials said Russia fired more than 70 missiles yesterday in one of its biggest attacks since the February 24 invasion of the Kremlin, causing emergency power outages across the country.

Klitschko also said that heating has been restored to half of the city and that electricity has been restored to two-thirds.

"But the emergency shutdown schedule is being implemented as there is still a power shortage," he wrote on the Telegram messaging app.

Klitschko earlier this month warned of an apocalypse scenario for the Ukrainian capital if Russian airstrikes on infrastructure continued, but also said there was no need for people to evacuate just yet.

"We are fighting and doing everything we can to make sure that doesn't happen," he said.