Officials spent three days searching a medium-security prison in southern Quebec, keeping the institution on lockdown the entire time.

A Corrections Canada official says staff at the Cowansville Institution are looking for what was described as unauthorized objects.

Claude Duguay added that while it's not unsual to search individual cells, prison-wide inspections are much more rare.

The lockdown began Friday and ended on Sunday.

Prisoners are isolated in their cells and visits have been suspended for the duration of the lockdown.