Inmates in a cell block at B.C.’s Kent Institution maximum security prison smashed the outside windows of their cells last week and as punishment were denied food and access to showers, CBC News has learned.

Inmates in the prison's A block broke the windows, prompting prison staff to deny food to the inmates Sept. 20 and denied them showers for four days.

On Monday, food was again withheld as punishment because inmates would not take down blankets draped over the broken windows and over their cell doors. Corrections officers considered the blankets a security threat as guards couldn't look into cells.

Sources told CBC News the disturbance was a result of high tension levels inside Kent.

The Correctional Service of Canada confirms there was what it calls "a minor disturbance" at Kent last week and that an investigation is underway.

The federal government's independent prison watchdog agency — the Office of the Correctional Investigator — is already probing the alleged assault of an inmate by guards at Kent.

In a statement to CBC News Thursday, chief investigator Howard Sapers said the office is investigating a number of complaints from inmates.

“It would be fair to conclude we have heightened concerns regarding this institution," Sapers said.

The prison houses more than 200 convicts, with more than one-third of them serving life sentences. The prison staff numbers about 360.

With files from Eric Rankin