Three children were killed in a major Ukrainian drone attack on the city of Krasnodar, in southern Russia, regional Governor Veniamin Kondratyev said on Monday.

He said the night-time attack sent drone debris crashing into a private centre for childcare, killing three children. Six were injured, while two adults were taken to hospital. The report could not initially be independently verified.

A warehouse, several houses and blocks of flats still under construction were also hit by falling drone debris, Kondratyev said.

The warehouse - which belongs to Ozon, Russia's second-largest online retailer - went up in flames. There were no casualties, the company said.

Drones struck other Ozon warehouses throughout Russia in the third consecutive day of strikes on the Ozon warehouses. At least four centres caught fire, more than ever before in a single day. The company's shares plummeted at the start of the week on the Moscow Stock Exchange.

The latest attacks come after Ukrainian strikes on logistics centres belonging to Russia's largest online retailer, Wildberries, causing billions in damage over several weeks.

The commander of the Ukrainian drone forces, Robert Brovdi, congratulated his country on the 35th anniversary of its independence following the strikes. "Moscow will fall!" he wrote on Telegram.

A total of 66 Russian targets were hit, including a fighter jet in the Rostov region, he said.

In Ukraine, power cuts were reported in six regions, including Odessa and Kharkiv due to Russian drone strikes on energy infrastructure. In Odessa, Governor Oleh Kiper reported major fires at two DIY stores and five people injured.

Ukraine has been defending itself against Russian attacks with Western military aid for four and a half years. The country marked the 35th anniversary of its independence from the Soviet Union on Monday, with European leaders including British Prime Minister Andy Burnham and European Council President António Costa gathering in Kiev.

Both sides make extensive use of drones in their attacks because they are relatively cheap to produce and can be difficult to intercept when launched in large numbers.

During some waves of attacks, hundreds of drones are deployed at the same time in an attempt to overwhelm air defences.

Russia and Ukraine regularly accuse each other of deliberately targeting civilians, although casualties and damage have been far greater in Ukraine.