The Department of Education, Sport and Culture has refused to reveal how much external validations at five schools cost.
A Freedom of Information request asked what a contractor cost to validate Castle Rushen High School, QEII High School, Kewaigue School, Peel Clothworkers' and St Mary's.
In its response the department said the validation is ongoing and it's not in the public interest to release information that could affect its ability to obtain the best value for money in future.
It added it also needs to protect the commercial interests of the private sector.
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