A day after Russia carried out the biggest aerial assault since the war started in February, Kyiv residents have been urged to head to air raid shelters as sirens wailed across the city.

Shortly after 2am on Friday, Kyiv’s city government issued an alert on its Telegram messaging app channel about the air raid sirens and called on residents to proceed to shelters.

Olekskiy Kuleba, governor of Kyiv region, said on Telegram that an “attack by drones” was under way.

A Reuters witness 20 kilometres south of Kyiv heard several explosions and the sound of anti-aircraft fire.

Kyiv officials said five Iranian Shahed drones were detected in the air and destroyed.

An administrative building was partly destroyed, said Serhiy Popko, head of Kyiv’s civilian military administration, but there was no information yet about casualties.

Merciless assaults

Kyiv says Iran is supplying Moscow with drones for its air attacks, but Tehran says it last sent drones to Russia before the war started.

The General Staff of Ukraine’s Armed Forces Friday morning report said Russia had launched 85 missile strikes, 35 air strikes, and 63 strikes from multiple rocket launch systems in the past 24 hours.

It said Moscow’s forces also shelled 20 settlements around the bombed out town of Bakhmut in eastern Ukraine, where some of the fiercest fighting is being waged, and more than 25 settlements in the Kherson and Zaporizhzhia regions.

Ukrainian President Volodymyr Zelenskiy said most regions hit in Thursday’s massive air attack suffered power outages.

Reuters footage on Thursday showed emergency workers searching through the smouldering wreckage of homes in Kyiv destroyed by a blast and smoke trails of missiles in the sky. Officials had earlier said more than 120 missiles were fired during Thursday’s assault.

More than 18 residential buildings and 10 critical infrastructure installations were destroyed in the latest attacks, the defence ministry said in a statement.

Waves of Russian air strikes in recent months targeting energy infrastructure have left millions of people without power and heating in often freezing temperatures.

The United States last week announced nearly $US2 billion ($A3 billion) in additional military aid, including the Patriot Air Defence System, which offers protection against aircraft, cruise and ballistic missiles.

British aid pledged

Britain on Friday said it has given Ukraine more than 1000 metal detectors and 100 kits to deactivate bombs and to help clear minefields.

Moscow has repeatedly denied targeting civilians, but Ukraine says its daily bombardment is destroying cities, towns, and the country’s power, medical and other infrastructure.

Russia invaded Ukraine on February 24 in what President Vladimir Putin calls a “special military operation” against what it perceives as threats to its security.

Ukraine and its Western allies have denounced Russia’s actions as an imperialist-style land grab and imposed sanctions to try to disrupt the campaign.

The 11-month war has killed tens of thousands of people, driven millions from their homes, left cities in ruins and shaken the global economy, driving up energy and food prices.

The heaviest fighting is in the eastern Donetsk and Luhansk provinces that together make up the industrial Donbas region. Russia claimed in September to have annexed them, along with the southern provinces of Kherson and Zaporizhzhia, but does not fully control any of them.

-AAP