Kyiv - Russia launched a wave of missile strikes across Ukraine, killing at least six civilians and forcing a nuclear power plant off the grid.

Ukrainian President Volodymyr Zelenskiy said critical infrastructure and residential buildings in 10 regions had been hit.

"The occupiers can only terrorise civilians. That's all they can do. But it won’t help them. They won’t avoid responsibility for everything they have done," Zelenskiy said in a statement.

At least five people were killed in a missile strike in the western Lviv region, and another civilian was reported killed in the central Dnipro region.

Kyiv residents were awakened by explosions, and a seven-hour air strike alert through the night was the longest of the five-month Russian air campaign.

Moscow says its campaign of targeting Ukraine's infrastructure far from the front is intended to reduce its ability to fight. Ukrainian officials said Moscow had fired six of its kinzhal hypersonic missiles, an unprecedented number, which Ukraine has no way of shooting down.

Ukraine said the missiles had knocked out the power supply to the Zaporizhzhia nuclear power plant, Europe's largest, severing it from the Ukrainian grid.

The plant, which Russia has held since capturing it early in the war, is near the front line, and both sides have warned of a potential for nuclear accidents there caused by fighting. Russian installed officials called the cut-off a Ukrainian provocation, and said the plant was running safely on diesel backup power.

Kyiv, the Black Sea port of Odesa, and the second-largest city Kharkiv were all hit as missiles targeted a wide arc of targets, stretching from Zhytomyr, Vynnytsia, and Rivne in the west to Dnipro and Poltava in central Ukraine, officials said. Ukrainian said it air defences had shot down drones and cruise missiles.