A 71-year-old Saskatchewan jail guard has been charged with sexually assaulting a prisoner after security video captured unusual activity in the cellblock.

The commander at the Meadow Lake RCMP detachment was conducting a routine review of cellblock area video footage Tuesday when he saw "what appeared to be on the on-duty guard removing an adult female prisoner from the cellblock area," the RCMP said in a news release.

"This was not an activity that was required as part of his duties."

Dennis Bienvenue, of Meadow Lake, is charged with one count of sexual assault. He is due to appear in court on June 8.

Bienvenue was working as a guard through the Corps of Commissionaires, a not-for-profit organization that hires former Canadian Forces and RCMP members for security jobs.

His employment at the Meadow Lake detachment was terminated Tuesday.