Authorities in Mykolaiv, the western city of Lviv and the Black Sea port of Odesa said air defences were trying to shoot down incoming missiles. Explosions were heard in the central Vynnytsa region, Ukrainian public broadcaster Suspilne reported.

    Moscow, which invaded last February, has been pounding Ukraine's energy infrastructure with missiles and drones since October, causing sweeping blackouts and disruptions to central heating and running water as winter bites.

    No one was reported hurt following the first wave, but missile debris caused a fire in one place and houses were damaged outside the capital, officials said.

    "An infrastructure facility was hit. No critical damage or fire. All emergency services are working at the site. No one is wounded," Kyiv's military administration said in a statement.

    Ukrenergo, which runs the power grid, said its workers were racing to fix the damage and that the network was grappling with a power deficit caused by earlier attacks even though it was -2 Celsius (28 Fahrenheit) in Kyiv, only mildly cold.

    DTEK, the biggest private electricity company, introduced emergency blackouts in Kyiv, the Kyiv region and Odesa region.

    Kyiv's mayor said the debris of a missile came down on a non-residential area in the Holosiivskiy district in the west of Kyiv, causing a fire but hurting no one.

    Residential infrastructure was also hit in the village of Kopyliv in the region just outside the capital. The windows and roofs of 18 privately owned houses were shattered or damaged by the blast, Oleksiy Kuleba, the regional governor, said.

    Air Force spokesperson Yuriy Ihnat said Russia's missiles had likely been fired along a high, looping ballistic trajectory from the north, which would explain why the air raid siren did not sound.

    Ukraine is not able to identify and shoot down ballistic missiles, he told the Ukrainska Pravda online outlet.

MISSILES STRIKE KHARKIV

    In Ukraine's northeast, Oleg Synehubov, Kharkiv's regional governor, said two S-300 missiles struck the city near the Russian border early on Saturday.

    The attacks hit critical energy infrastructure and industrial facilities in the Kharkiv and Chuhuev district of the region, he said.

    "Our emergency services units and energy workers are working to liquidate the consequences and stabilise the situation with energy supplies," he said.

    The strikes on Saturday came as Ukrainian and Russian forces battled for control of Soledar, a small salt-mining town in eastern Ukraine that for days has been the focus of a relentless Russian assault.

    Russia said on Friday that its forces had taken control of Soledar, in what would be a rare success for Moscow after months of battlefield reverses, but Kyiv said its troops were still fighting in the town.

    Reuters could not immediately verify the situation in Soledar.