The union representing workers at B.C. corrections facilities says housing newly-arrived refugee claimants will put a strain on an already severely overcrowded jail system.

Dean Purdy, chair of the B.C. Government and Service Employees' Union, said Friday housing the 490 passengers on the MV Sun Sea will push some facilities to more than four times their intended capacity.

"Adding hundreds more people to the facility at this time will severely test our ability to manage a safe facility," Purdy told ctvbc.ca.

Men from the MV Sun Sea will be housed at the Fraser Regional Correctional Centre in Chilliwack, east of Vancouver. The centre currently houses 550 inmates, more than twice its maximum capacity. Purdy says adding an estimated additional 400 people will be detrimental to staff and inmates.

"Corrections officers are dedicated to public safety and will respond to the challenge," Purdy said.

"But it means our officers will have to work even longer overtime hours than usual due to recruitment and retention issues, and presents an increased safety risk for our members and the inmate population."

Women will be sent to the Alouette Centre, which Purdy says also holds double its intended population.

Purdy is calling for the provincial government to expand correctional facilities in British Columbia.