A police investigation is underway at King William's College in Castletown after a hidden camera was discovered.
College principal Martin Humphreys confirmed officers were called into the school when the digital recording device was found in a toilet area on Wednesday.
A pupil has been suspended and is currently being questioned about the incident, described by Mr Humphreys as 'a very serious matter'.
All parents have been informed.
In a statement, the principal says the priority for College now is 'to reassure the children and their parents and guardians that all proper steps have been taken'.
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