Children as young as 11 have been targeted by violence and beheaded in northeast Mozambique during an jihadist insurgency in the region, the charity Save the Children said.
The UK-based aid organisation said it was "outraged and deeply saddened" by reports that children had been targeted in the conflict in the gas-rich Cabo Delgado province.
The violence has claimed the lives of 2,600 people in the east African nation, half of them civilians, and displaced 670,000, according to Save the Children.
One mother, whose name was withheld to protect her identity, told the charity her 12-year-old son was beheaded as she hid with her three other children.
"That night our village was attacked and houses were burned," she said.
"We tried to escape to the woods, but they took my eldest son and beheaded him. We couldn't do anything because we would be killed too," the mother added.
A second mother said she had been unable to bury her son who was killed by armed men after she had to leave her home for her own safety.
"After my 11-year-old son was killed, we understood that it was no longer safe to stay in my village. We fled to my father's house in another village, but a few days later the attacks started there too," she said.
The charity said the situation had seriously deteriorated in the past 12 months with an escalation of attacks.
The humanitarian crisis in the beleaguered region has been exacerbated by a series of floods in 2020 and Cyclone Kenneth, which struck northern Mozambique a year earlier.
"Reports of attacks on children sicken us to our core," said Chance Briggs, Save the Children's country director in Mozambique.
"A major concern for us is that the needs of displaced children and their families in Cabo Delgado far outweigh the resources available to support them.
"Nearly a million people are facing severe hunger as a direct result of this conflict, including displaced people and host communities."
Jihadists, known locally as Al-Shabaab, have staged a series of attacks in Cabo Delgado since 2017 and pledged allegiance to the Islamic State organisation in 2019.
They have been accused of beheadings and desecration of bodies.
Government forces, which have been bolstered by private military companies, have also been accused by rights groups of atrocities that amount to war crimes.