At least 43 children have been killed by armed forces in Myanmar since February's military coup.
Rights organisation Save the Children group said the South East Asian country was in a nightmare situation, with the youngest known victim just seven years old.
A local monitoring group puts the overall death toll at 536.
The UN's envoy to Myanmar has warned of the risk of an imminent bloodbath as the crackdown intensifies.
The warning follows a flare-up in fighting between the army and ethnic minority militia in border areas.
The deadliest day of the conflict so far came on Saturday, when more than 100 people were killed.