A Russian drone has slammed into a block of flats in eastern Kyiv, killing six people and wounding dozens of others, during a wave of strikes throughout the Ukrainian capital.

As emergency workers sifted through the wreckage in the Lisovyi area, one Kyiv resident called Vita described how the drone had pierced the building, exploding on the other side.

Meanwhile, Ukraine stepped up its attacks on Russia's oil infrastructure, with drone strikes on one of its biggest export terminals in Novorossiysk, on the Black Sea coast.

Fire broke out at the Sheskharis oil refinery, and a ship and a block of flats were hit, officials said.

Krasnodar governor Veniamin Kondratyev said three crew members and another man were hurt in the attack which damaged the main oil depot and a container terminal.

Mayor Andrei Kravchenko declared a state of emergency and Reuters reported that oil exports were suspended.

President Volodymyr Zelensky said Ukraine had fired long-range "Long Neptune" cruise missiles during its attacks on Russia overnight, without specifying what they targeted.

Condemning Russia's overnight attacks as vile and calculated, Zelensky said about 430 drones and 18 missiles had been launched and dozens of high-rise buildings damaged.

A drone attack on a market at Chornomorsk in the south of the country killed two people.

In Kyiv, residential buildings came under attack "in practically every district", the head of the city's military administration Tymur Tkachenko said on Telegram.

He issued a warning to take shelter a minute after midnight local time on Thursday night, writing "it's loud in Kyiv".

The fire service in the Lisovyi neighbourhood said later the drone had hit the seventh floor of the residential building. When it exploded all the floors - from the eighth down to the fourth - collapsed, a spokesman told the BBC.

Vita said she saw four bodies being pulled out of the apartment a few doors down from hers: "I saw it with my own eyes."

Two cranes hoisted emergency workers outside the block, as crews combed through the destroyed building, throwing broken sections of wall and shattered glass to the ground.

Falling debris and fires damaged several high-rise apartment buildings, a hospital, school and administrative buildings, according to emergency services.

More than 40 people were rescued, they added, including 14 from a fire in a residential building. Another person was rescued after being pulled from beneath the rubble, they said.

Kyiv's energy infrastructure was badly hit, leaving some buildings in the capital without heat, officials said.

"The attack was massive, with drones, with ballistic [missiles], with lots of air defence working," Ukrainian MP Lisa Yasko told the BBC. "Very often there was the feeling that your bed was just shaking together with the windows."

Medical teams were deployed to all fires, officials said, while Mayor Vitali Klitschko said nine people were being treated in hospital with one man in an "extremely serious condition".

Ukraine's air force warned drones and guided bombs had been targeting several other regions, including Sumy.

The overnight strikes follow the deaths of six people in another Russian offensive less than a week ago that also damaged residential buildings and energy infrastructure.

Russia says its attacks on energy targets - now a familiar part of the war - are aimed at the Ukrainian military, although Kyiv has long rejected that claim.