An independent investigation commissioned by the Welsh government into nursing standards at Abertawe Bro Morgannwg University Health Board (ABMU) has identified a number of serious concerns about the quality of care and patient safety.
The review has been led by Professor June Andrews, a leading expert on elderly care from the University of Stirling.
It has also identified problems with clinical and managerial processes within ABMU.
The review team focused on the current position in the Princess of Wales and Neath Port Talbot Hospitals and reports of previous experiences of older people in the care of ABMU over a three year period.
The report said: "Some of the poor professional practice which was evident in the past is still happening on some of the wards of the Princess of Wales and Neath Port Talbot Hospitals today.
"This is unacceptable and requires immediate concerted action, in addition to the required longer-term cultural and behavioural change.
"It is important to make it clear that these concerns are not of a scale to warrant action being taken by the minister in respect of the current leadership of the board."
ABMU said they accept all the findings and recommendations of the June Andrews Report.
A spokeswoman for the board said: "ABM University Health Board again wishes to apologise unreservedly to patients, and their families or carers, who have been let down by the poor care described in the Andrews Report.
“While we believe most of our care is of a high standard, we openly acknowledge some care has been very poor; this is clearly unacceptable.
"The report makes very uncomfortable reading, and contains tough messages.
“The sort of poor care it describes cannot and will not be tolerated.
“High quality care must be consistently provided across all our wards and departments, in all our hospitals, and we will settle for nothing less. We are determined to put things right.”
The health board says a number of measures have already been put in place to improve care standards.