Inmates at crowded Ontario jails are getting violent, prompting lockdowns and calls by guards for more staff and protective gear.

"Inappropriate inmate behaviour and contraband searches" prompted the lockdown at the Algoma Treatement and Remand Centre in Sault Ste. Marie, ON, on Thursday, said a spokesperson for the Ministry of Community Safety and Correctional Services.

Brent Ross declined comment on what inmates were doing or what correctional officers were searching for.

"We don't speak to that due to security reasons," said Ross.

He was not aware of any inmates or officers being injured.

Prisoners will be kept confined to their cells until they "cease their inappropriate behaviour."

This comes after more than 150 frustrated inmates shocked guards by refusing to be locked in their cells at Elgin-Middlesex Detention Centre last week in London, ON.

The jail guards' union there said worsening conditions will likely lead to mass violence.

"There's going to be a riot within the next couple of months," said Trish Goden, president of Local 108 of the Ontario Public Service Employees Union, citing overcrowding and understaffing.

Meanwhile, the Ottawa jail is becoming increasingly violent as more gangsters and prisoners with mental health issues plague the facility, exacerbating overcrowding issues.

Jail guards want access to protective equipment and say the issues will likely only get worse.

- With files from Randy Richmond and Brian Kelly