Children in northern Mozambique displaced by the Islamist insurgency have been traumatised by their experiences, an international charity says.

Save the Children, which has been collecting the testimonies of Mozambican children, says some have experienced extreme violence, including the killing of their parents by militants.

More than a third of a million children have fled their homes because of the conflict, which began in 2017.

The charity says the children's behaviour changes frequently and some may never recover unless they receive mental health treatment.

The Islamist insurgents, known locally as al-Shabab, are believed to be linked to the Islamic State group.

They came to international attention in March when they seized the town of Palma, near huge natural gas fields.