According to a union spokesman, guards were locked out of a Melbourne psychiatric prison hospital by managers and this has put mentally ill criminals and the public at risk.

According to Health and Community Services Union, HCSU, Victorian secretary Lloyd Williams, casually employed guards had replaced custodial security guards at the Thomas Embling Hospital today.

People who are ordered by the courts to be kept for psychiatric assessment and care and treatment are at the 116-bed secure psychiatric hospital in Fairfield along with criminals who have a mental illness who are transferred from prison.

G4S security company takes care of the security here and there has been an industrial dispute between the company and guards and this has led to the lockout.

Williams said, “We don't know what the qualifications or skill and experience of these people are, but we are questioning their capacity to keep this facility safe. We think G4S management are leaving this facility at risk - risk for patients and the public”

Alternative service had to be managed as there was information about work bans today, according to a G4S spokeswoman.