Ukrainian parents who fear they will be killed by invading Russian forces have begun writing family details on the bodies of their children as war closes in. 

Images of children with writing scrawled on their bodies have emerged on social media in recent days as a grim reminder of the horrifying reality of the conflict. 

"Ukrainian mothers are writing their family contacts on the bodies of their children in case they get killed and the child survives," wrote Kyiv Independent journalist Anastasiia Lapatina alongside a picture from a Ukrainian family. 

She added that despite the horrors of war that confront millions of Ukrainian citizens, "Europe is still discussing gas" – a reference to the European Union's controversial decision to place sanctions on Russian goods and services but not to ban oil or gas exports. 

The images of young children caught up in war follow confronting first-hand accounts of the toll the war is having on young people. 

It was reported last week that children were among hundreds of people found dead in the Ukrainian town of Bucha and that the Kremlin's soldiers were "mutilating children". 

A reporter for The Guardian in Ukraine also reported that children were being used as "human shields" by Russian forces as they attempted to flee. 

A child with a cat looks out from a bus at a refugee centre in Zaporizhia, Ukraine. Photo / AP 

The newspaper reported that buses full of children were being placed in front of tanks in the village of Novyi Bykiv, not far from Chernihiv. 

Ukraine's human rights ombudsman Lyudmila Denisova said: "Cases of using children as cover are recorded in Sumy, Kyiv, Chernihiv, Zaporizhzhia oblasts." 

One of Ukraine's highest military officials Colonel Oleksandr Motuzyanyk went a step further, alleging Russians were using them as hostages in their trucks. 

"Enemies have been using Ukrainian children as a living shield when moving their convoys, moving their vehicles," he said. 

"Russian soldiers have used Ukrainian children as hostages, putting them on their trucks. They're doing it to protect their vehicles when moving. 

"There have been cases of brutal behaviour against minors been recorded, documented by Ukrainian and international institutions, and we'd like to emphasise that information in each and every case will be given to the national criminal courts and the occupiers will be brought to justice for each and every military and war crime they commit." 

Ukrainian President Volodymyr Zelensky said that was Russia was doing was the equivalent of "genocide". He also mentioned how children had been murdered by invading forces. 

"We know that thousands of people have been killed and tortured with extremities cut off, women raped, children killed," he told reporters. 

The atrocities in Bucha have not gone unnoticed by the West where US President Joe Biden called Monday for a "war crimes trial" and vowed tougher sanctions against Moscow. 

A child sits next to baby trolleys as people who fled the war in Ukraine and members of the Ukrainian diaspora pray during a mass in Krakow's Orthodox church. Photo / Getty Images 

Bombardments continued Monday including in southern Mykolaiv, where officials said Russian strikes killed 10 civilians and wounded 46, as Kyiv warned that Moscow was shifting its military focus and preparing a "full-scale" attack in the country's east. 

With momentum building for a stiffer European Union response beyond already unprecedented sanctions over Russia's invasion, European Commission chief Ursula von der Leyen said the bloc was ready to send investigators to gather evidence of possible war crimes in Bucha. 

- by Rohan Smith, news.com.au