Authorities say three assaults in as many weeks show security is out of hand at the Bunbury Regional Hospital.

The Health Services Union (HSU) has put the call out for more resources, saying the rising number of violent patients is putting staff at risk.

The HSU wants the number of emergency department security guards increased from two to three, and would like police to provide some extra support when they drop off problem patients.

Health Services Union WA secretary Dan Hill says police tend to leave immediately after they have delivered sometimes rowdy and uncontrolled patients, and it is adding extra risk for staff.

“We expect that's a staffing matter for the local police and we will be raising that very serious matter with the Commissioner for Police and asking for his response with respect to reports that we're hearing,” he told the ABC.

“Security officers believe they would be able to do the job in a much safer manner if the numbers of security officers on shift were increased and [we] believe there should be three security officers on each shift and that would assist the situation.”

The WA Country Health Service is expected to comment in due course.