Russian missiles blasted cities across Ukraine on Monday, damaging the country’s largest children’s hospital and other buildings in a fierce assault that interrupted heart surgeries and forced young cancer patients to take their treatments outdoors. At least 31 people were killed, officials said.

The daytime barrage targeted five Ukrainian cities with more than 40 missiles of different types, President Volodymyr Zelensky said on social media.

Ukraine’s air force said it intercepted 30 missiles. More than 150 people were wounded.

Strikes in Kryvyi Rih, Mr Zelensky’s birthplace in central Ukraine, killed 10 people and injured 47 in what the head of city administration, Oleksandr Vilkul, said was a massive missile attack.

Mr Zelensky said on social media: “It is very important that the world should not be silent about it now and that everyone should see what Russia is and what it is doing.”

Russia denied attacking the hospital and said the strikes hit military targets.

In a statement, US President Joe Biden called the missile strikes “a horrific reminder of Russia’s brutality.”

“It is critical that the world continues to stand with Ukraine at this important moment and that we not ignore Russian aggression,” the statement said.

Western leaders who have backed Ukraine in the war are holding a three-day Nato summit in Washington beginning on Tuesday.

They will look at how they can reassure Ukraine of the alliance’s unwavering support and offer Ukrainians hope that their country can come through Europe’s biggest conflict since the Second World War.

At the Okhmatdyt children’s hospital in Kyiv, rescuers are searching for people under the rubble of a partially collapsed, two-storey wing of the facility.

Kyiv mayor Vitali Klitschko said at least 16 people, seven of them children, were injured.

Rescuers search through rubble
A major Russian missile attack across Ukraine killed at least 20 people and injured more than 50 (AP)

On the hospital’s main 10-storey building, windows and doors were blown out and walls were blackened.

Blood spattered the floor in one room. The intensive care unit, operating theatres and oncology departments were all damaged, officials said.

Medical personnel and local people searched for children and medical workers. Volunteers formed a line, passing bricks and other debris to each other.

Rescuers, volunteers and medical workers run to a shelter
Fresh air raid alerts caused panic in the wake of the strike (AP)

The attack forced the hospital to shut down and evacuate. Some mothers carried their children away on their backs. Others waited in the courtyard with their children as calls to doctors’ phones rang unanswered.

A few hours after the initial strike, another air raid siren sent many mothers with their children hurrying to the hospital’s shelter.

Led by torchlight through the shelter’s dark corridors, mothers carried their bandaged children in their arms and medics carried them on trolleys. Volunteers handed out sweets in an effort to calm the children.

Russia’s defence ministry said the strikes targeted Ukrainian defence plants and military air bases and were successful. It denied aiming at any civilian facilities and claimed without offering evidence that pictures from Kyiv indicated the damage was caused by a Ukrainian air defence missile.

Since early in the war that is stretching into its third year, Russian officials have regularly claimed that Moscow’s forces never attack civilian infrastructure in Ukraine, despite what officials in Kyiv say and Associated Press reporting on the ground.

Rescuers work in the rubble
Several children were injured (AP)

Elsewhere in Kyiv, where seven of the city’s 10 districts were hit in the heaviest Russian bombardment of the capital in almost four months, the strikes killed seven people and injured 25, officials said.

About three hours after the first strikes, more missiles hit Kyiv and partially destroyed a private medical centre. Four people were killed there, Ukraine’s Emergency Service said.

The daylight attacks included Kinzhal hypersonic missiles, one of the most advanced Russian weapons, the Ukrainian air force said. The Kinzhal flies at 10 times the speed of sound, making it hard to intercept.

City buildings shook from the blasts. An entire section of a residential multistorey building in one district of Kyiv was destroyed, officials said. Three electricity substations were damaged or completely destroyed in two districts of Kyiv, energy company DTEK said.

The head of Ukraine’s presidential office, Andrii Yermak, said the attack occurred at a time when many people were in the city’s streets.