When a ten-year-old boy from Caldes de Montbui, near Barcelona, discovered his grandmother's stash of banknotes, he took it into school and distributed €100 notes among his classmates.
The alarm was raised after a teacher at the school noticed that several children were carrying the large denomination, a rarity in Spain and particularly unsuitable for the canteen.
They questioned the children and traced the source to the boy who had come across the money his grandfather had put aside to buy essential medical equipment.
The story came to light after the teachers at the Escola Montbui primary school created a WhatsApp group for parents asking for the money to be returned and the exchange was read on the radio programme Julia en la Onda on Onda Cero.
“This morning a fifth-form primary school pupil has distributed 100 euro notes he'd taken from his house.
'If your child has been given any of this money, please contact the school immediately so it can be returned to the pupil's family.
“More than €10,000 needs to be recovered. We ask for your utmost understanding and cooperation. This is not a joke.”
One of the parents of a child who had received some cash told the radio station: 'Yes, it's true. Unbelievable but true.'