Canada’s prison population has reached an all-time high , with more inmates sharing cells designed for one, a situation that has raised tensions and led to growing violence, Canada’s correctional investigator says.

Howard Sapers, an ombudsman for inmates, presented the latest figures during a weekend national symposium on prison overcrowding in Ottawa that drew about 80 of Canada’s top criminologists, lawyers and prison experts.

As of July 31, there were 15,097 inmates in federal prisons, a "historic high," according to Sapers.

In the past two years, 1,000 new inmates entered the system, even though there were no new beds. Sapers described that number as equal to the population of two medium-security prisons, yet the system has had to absorb them.

Sapers added that overcrowding is most acute on the Prairies.

"Of the growth, 52 per cent has come from the Prairies. It’s the fastest-growing region in the country and aboriginal offenders account for most of the increase and account for 43 per cent of the offenders in that region," he said.

Howard Sapers, Canada's ombudsman for prisoners, says spiralling inmate numbers in federal facilities has led to an overcrowding problem that's 'contrary to staff and inmate safety.' (Sean Kilpatrick/Canadian Press)

The influx has led to an increase in double bunking, even in maximum-security units and in segregation in Manitoba’s Stony Mountain Institution and in the Saskatchewan Penitentiary in Prince Albert, two of the largest institutions on the Prairies. In those cases, Sapers said, some inmates have been forced to share a cell that is less than five square metres.

Sapers told CBC News that overcrowding has led to growing tensions and violence.

"We’re seeing an increase in the use of force, an increase in assaults, an increase in sick leave and stress leave among staff, we’re seeing an increase in lockdowns and exceptional searches."

Over the past five years, assaults in the Prairie region are up 90 per cent, from 306 in 2007 to 583 in 2012. The number of incidents involving use of force by staff rose 95 per cent in the same period.

Justice, corrections systems 'under strain'

"Putting two inmates in a single cell means an inevitable loss of privacy and dignity, and increases the potential for tension and violence. It’s a practice that’s contrary to staff and inmate safety," he said.

The increase in prisoners comes even before the full force of the government’s new tough-on-crime laws take effect, and that means the situation is likely to get worse, according to Kim Pate, executive director of the Canadian Association of Elizabeth Fry Societies.

"The justice system and the corrections system is already under strain in this country," added Catherine Latimer, executive director of the John Howard Society of Canada. "Corrections workers and even some provincial governments are telling us there is no room for more prisoners."

Corrections officials have acknowledged the problem and have admitted they are hard-pressed to deal with the growing numbers. The federal government has undertaken a plan to spend $600 million on 2,700 new cells in prisons across Canada, but that will take several years. At the same time, the government has announced cuts to the budget of the correctional service.

Until recently, Canadian corrections officials allowed a few cases of double bunking but only in extraordinary circumstances. Now, it has become common, even though it is contrary to the Minimal Standards for Prisoners as set out by the United Nations, according to Allan Manson, a law professor at Queen’s University in Kingston, Ont.

Manson said there is a possibility a prisoner could try to find the Canadian government liable for failing to follow its own laws to provide adequate care and protection for inmates. "The [Corrections and Conditional Release] Act is rife with standards that can’t be maintained as the numbers go up," he said.