A RUSSIAN attack has severely damaged a maternity hospital in the port city of Mariupol, Ukraine has said, as warnings were issued that Vladimir Putin could turn to chemical weapons.

Ukraine’s President Volodymyr Zelensky warned that there were “people, children under the wreckage” in Mariupol, as he branded Putin’s attack on the hospital an “atrocity”.

Western officials warned of their “serious concern” that Putin could use chemical weapons in Ukraine to commit further atrocities during the invasion.

Their assessment was that an “utterly horrific” attack on the capital of Kyiv could come as Russian forces overcome the logistical issues suspected of delaying their attacks.

Video footage shared by Mr Zelensky showed cheerfully painted hallways strewn with twisted metal and room after room with blown-out windows. Floors were covered in wreckage. Outside, a small fire burned and debris covered the ground.

Mariupol’s city council said on its social media site that the damage was “colossal”.

Ukraine Foreign minister Dmytro Kuleba called it a “petrifying war crime”, as he pleaded for allies to supply Ukraine with aircraft.

Boris Johnson said there are “few things more depraved than targeting the vulnerable and defenceless” as he reiterated that the UK was exploring more support to help Ukraine defend against airstrikes.

A Western official warned that “we’ve got good reason to be concerned about possible use of non-conventional weapons, partly because of what we’ve seen has happened in other theatres”.

They added: “As I’ve mentioned before, for example, what we’ve seen in Syria, partly because we’ve seen a bit of setting the scene for that in the false flag claims that are coming out, and other indications as well.

“So it’s a serious concern for us.”

Authorities had earlier announced new cease-fires to allow thousands of civilians to escape from towns around Kyiv as well as the southern cities of Mariupol, Enerhodar and Volnovakha, Izyum in the east and Sumy in the northeast.

Previous attempts to set up safe evacuation corridors largely failed because of Russian attacks. But Putin, in a telephone call with Germany’s chancellor, accused militant Ukrainian nationalists of hampering the evacuations.

It was not immediately clear whether anyone was able to leave other cities on Wednesday, but people streamed out of Kyiv’s suburbs, many headed for the city centre, even as explosions were heard in the capital and air raid sirens sounded repeatedly. From there, the evacuees planned to board trains bound for western Ukrainian regions not under attack.

Civilians trying to escape the Kyiv suburb of Irpin were forced to make their way across the slippery wooden planks of a makeshift bridge after the Ukrainians blew up the concrete span days ago to slow the Russian advance.

With sporadic gunfire echoing behind them, firefighters dragged an elderly man to safety in a wheelbarrow, a child gripped the hand of a helping soldier, and a woman inched her way along cradling a fluffy cat inside her winter coat. They trudged past a crashed van with the words “Our Ukraine” written in the dust coating its windows.

“We have a short window of time at the moment,” said Yevhen Nyshchuk, a member of Ukraine’s territorial defence forces. “Even if there is a cease-fire right now, there is a high risk of shells falling at any moment.”

In Mariupol, local authorities hurried to bury the dead in a mass grave. City workers dug a trench some 25 metres long at one of the city’s old cemeteries and made the sign of the cross as they pushed bodies wrapped in carpets or bags over the edge.

Nationwide, thousands are thought to have been killed, both civilians and soldiers, in the two weeks of fighting since Putin’s forces invaded. The UN estimates more than two million people have fled the country, the biggest exodus of refugees in Europe since the end of the Second World War.

The fighting knocked out power to the decommissioned Chernobyl nuclear plant, raising fears about the spent fuel that is stored at the site and must be kept cool. But the UN nuclear watchdog agency said it saw “no critical impact on safety” from the loss of power.

The crisis in Ukraine is likely to get worse as Russian forces step up their bombardment of cities in response to stronger than expected resistance. Russian losses have been “far in excess” of what Putin and his generals expected, CIA director William Burns said on Tuesday.

An intensified push by Russian forces could mean “an ugly next few weeks”, Mr Burns told a congressional committee, warning that Mr Putin is likely to “grind down the Ukrainian military with no regard for civilian casualties”.

UK Defence Secretary Ben Wallace echoed those comments, telling MPs that Russia’s assault will get “more brutal and more indiscriminate” as Putin tries to regain momentum.

The Ministry of Defence said fighting continued northwest of Kyiv. The cities of Kharkiv, Chernihiv, Sumy and Mariupol were being heavily shelled and remained encircled by Russian forces.

Russian forces are placing military equipment on farms and amid residential buildings in the northern city of Chernihiv, Ukraine’s military said. In the south, Russians in civilian clothes are advancing on the city of Mykolaiv, a Black Sea shipbuilding centre of 500,000 people, it said.

The Ukrainian military, meanwhile, is building up defences in cities in the north, south and east, and forces around Kyiv are “holding the line” against the Russian offensive, authorities said.

In Irpin, a town of 60,000, police officers and soldiers helped elderly residents from their homes. One man was hoisted out of a damaged structure on a makeshift stretcher, while another was pushed toward Kyiv in a shopping cart. Fleeing residents said they had been without power and water for the past four days.