Blasts were reportedly heard in several cities as anti-missile systems shot down incoming missiles. According to Ukrainian officials Russia has fired some 100 missiles.
Intentional cuts to power supplies have been made in Odesa and Dnipropetrovsk in a bid to minimise any more damage to the country's battered energy grid.
This comes as France's defence minister Sebastien Lecornu on Wednesday pledged further military support to Kyiv in an audience with Ukraine's President Volodymyr Zelenskyy insisting his government's backing is unflagging.
Lecornu said support would include French army equipment and a €200 million euro fund allowing Ukraine to purchase weapons.
While France has been less vocal about its military backing for Ukraine than the US and the UK, Lecornu said Paris would give military equipment from the French army to Ukrainian troops but highlighted that this would not weaken France’s defences.
Paris could deliver a new air-defence system in the future, officials said, without revealing details, though Ukrainian Defense Minister Oleksii Reznikov added that France would immediately begin training Ukrainian air officers on how to use it.
Lecornu and Reznikov did not specify which new air defence system France could give Ukraine in the near future. But Lecornu later mentioned the MAMBA anti-missile system developed together with Italy, describing it as the European equivalent of the Patriot air defence system that the US has given Ukraine.
Reznikov said Ukraine's top priority remains “air defence, anti-missile defence, anti-drone defence, that is, the task of protecting (the) Ukrainian sky." French Crotale air-defence systems already are “on combat duty,” said Reznikov.
“And accordingly, we agreed that we will increase (the) capabilities of our air force,” he said.
Lecornu arrived a week after Ukrainian President Volodymyr Zelenskyy visited the US.
After a meeting with Lecornu, Zelenskyy expressed gratitude to France on social media “for the already provided military assistance aimed at protecting the Ukrainian sky and strengthening the capabilities of the defence forces.”
Earlier on Wednesday, in his annual speech to Ukraine’s parliament, Zelenskyy urged the European Union to open membership talks with his country after granting it candidate status in June. He also praised relations with Washington, saying its decision to send Patriot missiles is "a special sign of trust in Ukraine.”
France has supplied Ukraine with a substantial chunk of its arsenal of Caesar cannons, anti-tank missiles, Crotale air defence missile batteries and rocket launchers. It is also training some 2,000 Ukrainian troops on French soil.
French President Emmanuel Macron pledged last week to provide a new injection of weapons in early 2023.
Western military aid to Ukraine has angered Moscow. On Tuesday, Russian Foreign Minister Sergey Lavrov accused Washington and NATO of fueling the war with the aim of weakening Russia and warned the conflict could spin out of control.