The report, which covers the period from July 2020 to the end of 2023, confirmed over 5,140 "grave violations" committed against more than 4,000 children, some as young as three months old.

The figures mark a 400 percent increase over the previous period of September 2018 to June 2020, with a sharp rise since the military overthrow of the government in February 2021 and the subsequent resumption of fighting between the army and various armed ethnic groups.

The report attributed the vast majority of the abuses to Myanmar armed forces and affiliated groups.

"I am deeply alarmed by the surge in grave violations against children and the multiplication in the number of armed actors," Secretary-General Guterres said in the report.

"I am appalled by the scale of recruitment and use and by the surge in the killing and maiming of children, notably as a result of the widespread use of indiscriminate air strikes and firearms, explosive ordnance, in particular landmines, and the rise in attacks on schools and on hospitals by all parties to the conflict, in particular by the Myanmar armed forces," he added.

Guterres also called on all parties "to release all children from their ranks."

Cases of child recruitment accounted for about 40 percent of the violations, the report stated, with the phenomenon expanding to all states and regions following the coup.

The number of abductions of children also sharply increased, by nearly 3,000 percent, with many of those abducted being forced to undertake military training.

The report found that minors were also used to recruit other children, gather information or extort money, and serve as human shields for military forces.