The organisation which sets NHS standards has said that nurses in hospitals should not have to look after more than eight patients each at any one time.
Following concerns about standards of patient care in the aftermath of the Mid Staffs scandal, the National Institute for Health and Care Excellence (Nice) is to warn that any higher workload place on registered nurses' would put patients' safety could be put at risk.
The regulator's move will ramp up pressure on hospitals to hire more staff to tackle shortages even though many have little spare money, according to a report in the Guardian.
Susan Osborne, the chair of the Safe Staffing Alliance, which includes the Royal College of Nursing (RCN), the health union Unison and the Patients Association, said: "A 1:8 ratio still means that the nurse only has seven and a half minutes per patient per hour, which is too little.
"If it's more than eight then patients won't get fed, care plans won't get written, and nurses can't sit and talk to patients and reassure them about their condition. Care just won't be given to a proper standard, and patients can die."
But the deputy chief executive of the NHS standards watchdog said having one nurse to every eight patients is not a "magic number".
Gillian Leng of the National Institute for Clinical Excellence told ITV News that in many cases, such as in intensive care units, nurses should be caring for much fewer than eight patients at a time.
The Department of Health has defended the government's record on nurses.
A DoH spokeswoman said: "There are over 5,100 more nurses on our wards since 2010 and in response to the Francis Inquiry we have been tough on insisting on compassionate care in our hospitals."
But the number of NHS nurses on some wards is "wholly unsatisfactory" in "far too many cases", the head of the Royal College of Nurses has told ITV News.
Dr Peter Carter also warned that a new minimum standard of having eight patients for each nurse on duty would not solve staffing problems.
Dr Carter said that on some wards the ratio should be as low as one nurse per patient.