Russia carried out a series of drone strikes in Ukraine overnight, killing at least four people and wounding 20 in the capital Kiev, Ukrainian officials said.

"Kiev was subjected to another drone and ballistic missile attack. Rescue teams are working on the aftermath at several locations in the city," Ukraine's State Emergencies Service wrote on Telegram.

Kiev Mayor Vitali Klitschko said four people were confirmed dead and 20 injured in the capital, 16 of whom were hospitalized.

As a result of the shelling, several fires broke out in different areas, including an apartment building, civil infrastructure and a metal hangar.

The shelling damaged railway tracks in the Kiev region, with Ukraine's national railway operator warning of 90-minute delays.

Several strikes also hit the city of Lutsk in western Ukraine and the Ternopil region.

"Today the enemy conducted the largest air attack in our region so far. There have been multiple strikes," said Vyacheslav Negoda, head of the regional military administration in Ternopil.

"We have started putting out the fires and assessing the damage and other consequences."

Five people were wounded in the shelling in Lutsk.

"We also have many broken windows in private homes, several educational institutions and one damaged state building," the city's mayor, Igor Polischuk, wrote on Telegram.

Buildings and cars were also damaged in the western town of Khmelnitsky, according to the regional governor.

Russian leader Vladimir Putin has vowed to retaliate for Kiev's recent drone attack on Russian territory that destroyed billions of dollars worth of nuclear-capable bombers.

Meanwhile, Ukrainian strikes overnight against Russia wounded three people in the western region of Tula.

Russian air defense forces shot down a drone flying toward Moscow, the capital's mayor said.

"A total of ten enemy drones targeting Moscow were successfully repelled," Mayor Sergei Sobyanin said.

Putin appeared to rule out the possibility of a truce or direct talks with Ukrainian President Volodymyr Zelensky.

The Ukrainian leader said Moscow had issued an "ultimatum" to Kiev, demanding that Ukraine withdraw completely from four regions that Russia claims to have annexed but does not fully control. | BGNES