Two hundred children have been killed in Ukraine since Russian President Vladimir Putin ordered his troops to attack the country in late February, the office of Ukraine's Prosecutor General said in a statement on Saturday.
The office added that more than 360 children have been injured during the war so far.
Five children were injured and two of them died -- including a 7-month-old baby -- in a Russian strike on Kharkiv on Friday, the office said.
It added that a 15-year-old boy was injured on Thursday as a result of the detonation of a cluster munition on the outskirts of Novovorontsovka settlement in the Kherson region.
Earlier this week, UNICEF said that nearly two-thirds of Ukrainian children are now displaced due to the ongoing conflict.
UNICEF's emergency programs director Manuel Fontaine told the UN Security Council on Monday that he had "rarely seen so much damage caused in so little time" after returning from a visit to Ukraine.
They have been forced to leave everything behind: Their homes, their schools, and often, their family members," he said.
Fontaine said the UN had verified the deaths of 142 children with 229 injured as of Sunday, but that "the true figures are most certainly much higher given the scale of attacks."
He also drew attention to the 3.2 million children estimated to still be in their homes.
"Nearly half may be at risk of not having enough food," he said. "Attacks on water system infrastructure and power outages have left an estimated 1.4 million people without access to water in Ukraine. Another 4.6 million people have only limited access.
"The situation is even worse in cities like Mariupol and Kherson, where children and their families have now gone weeks without running water and sanitation services, a regular supply of food, and medical care. They are sheltering in their homes and underground, waiting for the bombs and violence to stop."
He also said unaccompanied children in Ukraine face a "much higher risk of violence, abuse, exploitation, and trafficking," and pointed to the impacts of school closures on 1.5 million students in higher education and 5.7 million school-age children.
CNN's Richard Roth and Yulia Kesaieva contributed reporting to this post.