The Department of Home Affairs says giving out information about prison staffing and procedures would undermine security at the Jurby facility.
A Freedom of Information request asked for details and policies about safe staffing levels and contingency plans for being short-staffed.
But in its response, the department said revealing the data could undermine the safety of inmates, officers and visitors.
And it added if it was made public, it could be used to identify operational vulnerabilities.
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