Patients are being put at risk because the NHS is employing a growing number of unregulated and untrained healthcare assistants, according to the chief executive of the Royal College of Nursing.
Peter Carter said the number of assistants, who help nurses with basic tasks such as washing and feeding, has grown "exponentially" over the past decade and that many are performing specialist procedures they learn "in-house" and are not formally trained to do.
In an interview with The Times he also claimed a growing number of newly qualified nurses were "simply not up to the mark" because they have spent too much time in the classroom and not enough on wards.
"What we have on hospital wards, and particularly in domiciliary care and care homes, is an unregulated, untrained workforce who are picking up so much of this on the job as they go along. Frankly, it's nothing short of a disgrace," he said.
"We (require regulation and training) in just about every other walk of life. Gas fitters have to be registered. But somehow when it comes to patient care we've got this unregulated, untrained workforce and then people wonder from time to time why there are problems."
Dr Carter, whose union represents both nurses and healthcare assistants, added: "You don't need registered nurses to do every task. But things like wound care, nutrition, hygiene, moving people in bed, these are techniques that need to be properly taught, and not something that should be picked up on the job."
The union head said it is "not fair" that many patients believe they are being treated by nurses when in fact they are being treated by healthcare assistant.
A Department of Health spokesman said: "The Government's view is that national statutory regulation must be proportionate and targeted - and we do not believe that this is the case for healthcare assistants.
"The Government intends to establish the Professional Standards Authority for Health and Social Care (currently the CHRE) as the national accrediting body for a system of assured voluntary registers for groups that are currently not subject to statutory professional regulation, which includes healthcare assistants."