Ukraine has endured a second night of deadly Russian air strikes just hours after a 'massive' bombardment saw energy infrastructure and civilian buildings destroyed by waves of drones and hypersonic missiles.

At least four people were killed in the strikes, including two confirmed dead after a missile attack 'wiped out' a four-storey hotel in the city of Kryvyi Rih.

Air raid sirens blared most of the night in the Ukrainian city, President Zelensky's hometown, as well as throughout central and eastern regions from 11pm on Monday.

The attack comes just days after another hotel used by civilians in the Donetsk region was targeted, resulting in the death of British ex-soldier Ryan Evans, a security adviser for Reuters.

President Zelensky said Russia had used over 90 aerial weapons, including 81 Iranian-made Shahed drones as well as as well as cruise and ballistic missiles.

'We will undoubtedly respond to Russia for this and all other attacks,' he said on X. 'Crimes against humanity cannot go unpunished. '

The Ukrainian leader yesterday condemned Moscow's 'vile' bombing campaign, declaring that Vladimir Putin's forces had launched at least 127 missiles and 109 drones on Monday in 'one of the largest Russian attacks' of the war.

Monday's onslaught killed seven, and left 47 people injured across the country. Some of the strikes sought to deprive civilians of electricity and water.

Pictures show rescuers continuing to work to locate two missing people at the Aurora Hotel, who are feared trapped beneath the rubble.

This morning, the Ukrainian air force confirmed early the takeoff of 'several' Tu-95MS bombers from the Engels airfield in western Russia. 

Ukrainian air defences shot down about 15 drones and several missiles near Kyiv during Russia's overnight attack, according to Serhiy Popko, head of Kyiv's military administration.

US President Joe Biden described the strikes as 'outrageous' but the Washington-based think tank Institute for the Study of War, predicted that Moscow 'likely lacks the defence-industrial capacity to sustain such massive strikes at a similar scale with regularity'.

The latest attacks are seen as reflecting Putin's wrath at Ukraine occupying a swathe of territory inside Russia, in Kursk region.

President Zelensky called for him to be given Western permission to launch long-range strikes inside Russia with missiles supplied by NATO nations.

Poland revealed that an unidentified 'aerial object' flew into its air space during the Russian bombardment.

General Maciej Klisz, operational commander of the armed forces, said at least three radar stations had registered the suspected drone.

The army was in 'full control' of the situation and was ready to shoot the object down if necessary, he said.

A search has been launched in case the object came down on Polish territory.

The incursion was near the Ukrainian town of Chervonohrad.

In Russia, meanwhile, officials reported a Ukrainian drone attack overnight.

Four people were injured in the central region of Saratov, where drones hit residential buildings in two cities. 

One drone struck a residential high-rise in the city of Saratov, and another hit a residential building in the city of Engels, home to a military airfield that had been attacked before, local officials said.

Russia's Defense Ministry said a total of 22 Ukrainian drones were intercepted overnight and in the morning over eight provinces, including the Saratov and Yaroslavl regions in central Russia.

Russia also said its troops had fended off Ukrainian attempts to advance on half a dozen settlements in the Kursk region, where Ukraine launched an incursion on Aug. 6 that caught Russia off-guard.

The fighting in the region has raised concerns about the nuclear power plant there. International Atomic Energy Agency chief Rafael Grossi said he would visit the plant Tuesday.