(Reuters) - Russia launched several waves of drone attacks on Kyiv early on Sunday for the second night in row, stepping up its assaults on the Ukrainian capital after several weeks of pause, the city's military administration said.

"The enemy's UAVs (unmanned aerial vehicles) were launched in many groups and attacked Kyiv in waves, from different directions, at the same time constantly changing the vectors of movement along the route," Serhiy Popko, head of the Kyiv's military administration, said on the Telegram messaging app.

"That is why the air raid alerts were announced several times in the capital."

Popko said that according to preliminary information Ukraine's air defence systems hit close to 10 Iranian-made Shahed kamikaze drones in Kyiv and its outskirts.

There have been no initial reports of "critical damage" or casualties, he said.

Reuters could not independently verify the reports. There was no immediate comment from Russia.

Russia started carrying out strikes on Ukraine's energy, military and transport infrastructure in October 2022, six months after Moscow's troops failed to take over the capital and withdrew to Ukraine's east and south.

Over last winter, Russia pounded Ukraine with hundreds of missiles and drones, leaving millions without electricity, heating and water during the coldest months of the year - before easing the assaults in the summer.

After a pause of 52 days, Moscow resumed air strikes on Kyiv earlier this month. On Saturday, Ukrainian officials said all drones heading towards Kyiv were destroyed, but some hit infrastructure facilities elsewhere in Ukraine.

President Volodymyr Zelenskiy and other officials have warned that Russia would resume its large-scale bombardments of Ukrainian civilian infrastructure during the winter months.