TORONTO -- Some jail guards are brutalizing inmates and covering up the abuse by destroying or falsifying records and intimidating colleagues, Ontario's ombudsman warned Tuesday.

In a report on jailhouse brutality, Andre Marin called for immediate action to root out the problem and excise the "cancer" of the code of silence around guard violence.

"Punching, slapping, kicking, stomping on someone who is under control, under restraints, is inexcusable and morally repugnant," Marin said.

"Regardless of why they are incarcerated, inmates are human beings and they deserve respect, dignity and humane treatment."

Marin's 135-page report is the product of thousands of complaints a year that were paralyzing his office.

Filled with disturbing pictures and stories, it outlines a grim reality in Ontario's 29 correctional facilities in which, Marin said, guards can assault inmates, often with complete impunity because their fellow officers don't speak up.

"This report is not pretty. It reveals some shocking stories -- not just of violence within the provincial correctional system but of ugly conspiracies to cover up that violence," he said.

"It exposes corruption and a malignancy within the correctional system that has long been lamented but never eradicated: the code of silence."

Marin cited the example of "Colin," an inmate with a brain injury who was acting aggressively toward guards at a facility in Ottawa.

Six officers restrained him with handcuffs and leg restraints, then beat him to a pulp, leaving his head swollen, his face and body battered. Guards initially claimed the prisoner hit his head on the floor.

Marin was careful to blame a "rogue minority" of correctional officers who bully inmates and colleagues, but he said the aberrant behaviour has been allowed to metastasize throughout the prison system.

Part of the problem, the report finds, is overcrowding and understaffing in the province's jails that exacerbate tensions. The government, Marin said, had let the "system run amok."

The report makes 45 recommendations to the provincial government to end the "dysfunctional culture," among them better training, especially in dealing with prisoners with mental-health issues or other special needs.

Also needed is wider use of video surveillance, so guards know they are being watched and more rigorous investigations of complaints, the report said.

The government, Marin said, must focus on "malignant" peer pressure among some correctional officers.

The ombudsman, who spent years overseeing the military and police, said the extent of the code of silence among prison guards is unprecedented in his experience.

"I've never seen it so entrenched, so pervasive."

Statements from guards, he said, are vetted by their union and read like a template. Another recommendation calls for staff involved in an incident to be separated before they prepare their reports and barred from communicating with one another until after the investigation is completed.

Two summers ago, the Ministry of Correctional Services began a review of more than 3,500 files involving alleged excessive use of force and investigated 55 cases. The probe confirmed brutality in 26 of those cases.

The result was discipline against 108 staff, including 31 firings. In addition, four officers face criminal charges, and one has been convicted.

Correctional Services Minister Madeleine Meilleur said the government has already begun taking action and six internal investigations into complaints are ongoing.

"We are taking this issue very seriously," Meilleur said. "One incident is too many."

The government is setting up an oversight and investigation unit, and appointing a use-of-force auditor to enhance oversight and accountability.

The government, she said, is also implementing a zero-tolerance policy for any behaviour that threatens inmate safety or intimidates other guards.

Warren (Smokey) Thomas, the president of the Ontario Public Service Employees Union, welcomed Marin's recommendations.

"We have said to the employer for decades: 'You have the tools at your disposal to deal with problem staff and we want you to deal with problem staff'," Thomas said.