Saskatchewan Penitentiary at Prince Albert, Sask., houses about 700 medium- and maximum-security inmates. (CBC)

Thirty jobs are being cut at Saskatchewan's federal prisons, the union representing prison workers says.

That includes 17 positions at Saskatchewan Penitentiary in Prince Albert, five at Riverbend Institution in Prince Albert and eight at the Regional Psychiatric Centre in Saskatoon.

Job "affected" notices have been handed out, said John Edmunds, national president of the Union of Solicitor General Employees.

The 100-year-old Saskatchewan Penitentiary is already overcrowded and the workers have workload issues, Edmunds said.

"They're professionals beyond belief," he said. "They know what they're doing and to pretty much have the rug pulled out from under them at this point in time ... it's a very difficult scenario."

Calls to the Correctional Service of Canada, the federal government branch that runs the prisons, were not immediately returned.

Earlier this week, the federal government said it would be closing Kingston Penitentiary in Ontario and two other facilities.