More than half of Ukrainian children have been displaced since Russia invaded Ukraine, according to the United Nations' Children's Fund (UNICEF).
Around 4.3 million children -- more than half of the country's estimated child population of 7.5 million -- have been displaced in the one month since the war started.
It includes around 1.8 million children who have fled to neighbouring countries and 2.5 million who are displaced within Ukraine, according to the UN agency, which is focused on providing humanitarian aid to children.
"The war has caused one of the fastest large-scale displacements of children since World War II," said UNICEF's executive director Catherine Russell in a statement.
"This is a grim milestone that could have lasting consequences for generations to come. Children's safety, wellbeing and access to essential services are all under threat from non-stop horrific violence."
The war has also resulted in the deaths of at least 128 children since the start of the war, according to Lyudmyla Denisova, Ukraine's human rights commissioner.
Another 172 children have been injured since the war began, Denisova said, adding however that the actual number is likely much higher.
Russell said in a speech earlier this week, that "inside Ukraine, children and their families are hiding in basements and sheltering in train stations".
"Millions have little to no access to safe water, or adequate sanitation and hygiene. Millions of children have been out of school," Russell added.
Over 450,000 children aged 6 to 23 months need complementary food support, UNICEF said, and the agency has also observed a reduction in vaccination coverage in children.
"In just a few weeks, the war has wrought such devastation for Ukraine's children," said Russell.
UNICEF is working to reach children and families inside the country, dispatching emergency supplies and aid. They are appealing for an immediate cease-fire.