Doctors and nurses found guilty of "wilful neglect" of patients could face jail, the government is proposing.
Wilful neglect will be made a criminal offence in England and Wales under NHS changes next week following the Mid Staffordshire and other care scandals.
The offence will be modelled on one punishable by up to five years in prison under the Mental Capacity Act.
Doctors' leaders said the threat of criminal sanctions could create a climate of fear in the NHS.
The government's proposals are due to be unveiled next week.
Prime Minister David Cameron said health workers who mistreated and abused patients would face "the full force of the law" in a package of measures.
A consultation on what scale of sentence should be applied to the extended law will be carried out over the next few months.
The move was one of the recommendations of a review of patient safety commissioned by ministers after findings that hundreds suffered unacceptable treatment at Mid Staffordshire NHS Foundation Trust.
It was led by Professor Don Berwick, a former adviser to US president Barack Obama, who said that patient safety must become the top priority and the measure was needed to target the worst cases of a "couldn't care less" attitude that led to "wilful or reckless neglect or mistreatment".
Many of his recommendations focused on created a new culture of openness and transparency.
Mr Cameron said the NHS was full of "brilliant" staff but the Mid Staffordshire case showed care was "sometimes not good enough".
"That is why we have taken a number of different steps that will improve patient care and improve how we spot bad practice," he said.
"Never again will we allow substandard care, cruelty or neglect to go unnoticed".
Shadow health secretary Andy Burnham said the proposal should be introduced alongside the package of measures detailed in Sir Robert Francis's public inquiry report into failings at Stafford Hospital, including minimum staffing levels.
He warned against the government adopting a "pick and mix" approach.
He also urged them to "tread carefully" to avoid denigrating staff.
A spokesman for the Welsh government said it would not comment until it had seen the proposals on Tuesday.
The British Medical Association (BMA) said doctors and nurses might be less likely to speak out against colleagues if they thought they would go to jail as a result.
Dr Andrew Collier, co-chairman of the BMA's junior doctors' committee, said doctors who failed to meet certain standards needed support and help.
"They don't need this new climate of fear. They don't need to be concerned that they may be sent to jail. What they need to do is learn from their mistakes and develop their practice," he told BBC Breakfast.
He called the move a "headline-grabbing exercise" and said it did not address the other recommendations made by Prof Berwick, such as minimum staffing levels and culture changes.
Dr Maureen Baker, the new chairman of the Royal College of GPs, said: "Doctors, nurses - we are human. Human beings make mistakes.
"You can't change the human condition, but you can help support the humans in having systems around them that help keep them safe, caring and compassionate."
Peter Carter, general secretary of the Royal College of Nursing, said a law change on its own was "not a panacea".
He added that legally enforced staffing levels would have a far greater impact on patient care, as they had in Australia and California.
But Julie Bailey, who founded pressure group Cure the NHS to expose failings at Stafford Hospital following her mother's death there, welcomed the government's proposal, saying: "Now it's time for patients' safety to be a priority."
A spokeswoman for the Scottish government said: "We will analyse these proposals once published by the UK government and will consider if further legislation is required in Scotland to supplement the existing arrangements of professional regulation."
Peter Walsh, chief executive of patient safety charity Action Against Medical Accidents, welcomed the possibility of prison sentences for neglect, but said a "much more joined-up approach" was needed.
He said the "full set of recommendations" from Sir Robert Francis's inquiry must be implemented.
Mr Walsh said he hoped the latest announcement was not intended to distract attention from some of the "more difficult" recommendations the government "may be reluctant to implement", such as minimum staffing levels.
He rejected the BMA's suggestion the new law might make people more reluctant to report colleagues, saying he had "more faith in the medical profession" than that.
Any new rules must apply to everyone in health organisations - from the "board to the ward" - he added.
Last month, the World Medical Association, which represents 102 national medical associations, condemned government attempts to control how doctors practise medicine, including criminalising medical decision-making.