Queensland's two largest hospitals have spent much of Friday on "code yellow" as pressure mounts while health authorities grapple with fixing a sterilisation malfunction at one of the facilities.

Key points: A hospital is declared code yellow when it is full and cannot meet public demand

A hospital is declared code yellow when it is full and cannot meet public demand Royal Brisbane and Women's Hospital was code yellow due to an "acute shortage of bed capacity"

Royal Brisbane and Women's Hospital was code yellow due to an "acute shortage of bed capacity" Princess Alexandra Hospital on Brisbane's south side was placed on code yellow last week because of sterilisation issues

Early in the day, the Royal Brisbane and Women's Hospital (RBWH) became the latest to be placed on alert after an "acute shortage of bed capacity" in the past 24 hours.

"We are experiencing a high level of demand for beds, and staff are asked to focus on clinical priorities and facilitate discharge where appropriate," a memo to staff read on Friday morning.

A code yellow declaration is made when a hospital is full and cannot meet public demand for the local area health service.

The Princess Alexandra Hospital (PAH) on Brisbane's south side was placed on code yellow a week ago because of issues with sterilisation equipment at the facility.

The code yellow at RBWH was a result of the PA Hospital sterilisation issue. ( ABC News: Julie Hornsey )

RBWH was eventually taken off code yellow late on Friday afternoon.

Dozens of surgeries have been cancelled since sterilisation machines at the hospital were taken offline, but Queensland Health is refusing to reveal exactly how many have been postponed.

An internal email obtained by ABC News showed patients have been transferred to other hospitals, potentially adding to capacity issues elsewhere.

"All patients that may require a surgical admission should be assessed in ED (the emergency department) as requested by ED staff," the email stated.

"If the patient requires admission, arrange transfer to another facility.

"Generally outpatients will be deferred until the hospital is back to normal activity."

A Queensland Health spokesman said staff are working to resolve the increased demand.

"Being on code yellow enables the PAH to be provided with additional support to return services to full capacity following the disruption to sterilisation services since 22 August," the spokesman said.

"As Metro South indicated on Tuesday — there would be a gradual return to normal elective surgery volumes over the coming week."

'This is unacceptable'

Opposition Leader Deb Frecklington said patients deserved to know when surgeries would resume.

"Now we hear the RBWH is on code yellow like the PAH — this is unacceptable," she said.

"It is a distressing situation, there are many people that desperately need these operations and it's unacceptable that they've now been pushed back down the list, and I really feel sorry for them."

Earlier this year, Premier Annastacia Palaszczuk and Health Minister Steven Miles personally appealed to residents to avoid going to emergency departments in South-East Queensland unless they were critically ill, after a number of hospitals were placed on code yellow during of a spike in demand.