More than 100 firefighters and emergency workers in southern Spain are searching for a 2-year-old toddler who fell into a narrow and deep well.

Spain's government representative in the Malaga province, Maria Gamez, says firefighters have found a bag of sweets that the boy was carrying when he went missing in the early Sunday afternoon (Monday morning NZ time).

Rescuers believe the boy fell into the 100-metre-deep waterhole in a mountainous area near the town of Totalan after he walked away from his parents.

The shaft, which is too narrow for an adult to enter, had been bored a month earlier during water prospection works and had not been covered or protected, local media are reporting.

Gamez says that rescuers are trying to avoid blocking the small diameter of the well with falling soil as they search for the boy.