A call has been made for an inquiry into claims patients are refusing food at a Swansea psychiatric hospital.
The kitchens at Cefn Coed Hospital closed in September last year
It is claimed some elderly patients have lost weight following the closure of the kitchens at Cefn Coed Hospital.
The Royal College of Nursing said Swansea NHS Trust must ensure people there were adequately fed.
The trust said while it took the issue 'very seriously', there was no evidence linking claims of weight loss with the change in food provided.
The kitchens at Cefn Coed closed in September last year as Swansea NHS Trust changed to what it called a "cook chill" system.
This saw meals prepared at another site and re-heated at Cefn Coed.
Marilyn Hancock, whose 89-year-old mother has been a patient there for two years, said she had been forced to take meals in for her as she was not eating what the hospital was providing.
"The staff are wonderful and the patients are really well looked after but morale is very low," she said.
"I've seen them making sandwiches for the patients because they will not eat the food. I've been taking cooked dinners in for my mother."
Old and frail
Mrs Hancock claimed several patients on Ward A at the hospital, which she said was scheduled to close, were not eating the food provided.
Some of the patients on the ward were old and frail and had dementia.
Another relative, who contacted the BBC News website but asked not to be named, alleged she had seen a deterioration in the physical health of her father since the changes.
Swansea NHS Trust said the system introduced at Cefn Coed was one that had operated successfully at many hospitals across the UK.
It was also used at Singleton, Hill House, Fairwood and Gellinudd hospitals in the city.
"We have put in place measures to monitor both the volume and quality of food and steps to improve the link between the catering staff, ward staff and senior nursing staff to ensure that the particular needs of psychiatric patients are met," it said in a statement.
"Concerns have been raised about potential weight loss by patients, although there is no evidence that this is related to the food provided.
"We are however taking this matter very seriously and the acting director of nursing, along with senior nurse colleagues at Cefn Coed Hospital, are working with dieticians and ward staff to ensure that patients are not being put at risk."
Richard Jones, deputy director of the Royal College of Nursing. said he was looking into the claims and hoped to meet with the trust.
"It is essential that the trust takes immediate action to investigate these concerns and to ensure that all patients dietary requirements are met in full.
"It is not acceptable for patients to be presented with meals that are unpalatable.
"Nutrition is an absolute essential component to enable patients to rehabilitate their illness."