By Nick Triggle
BBC News health reporter
Reviews are being carried out across the country
At least 10 major hospitals in England face potential closure or a downgraded role, the BBC has learned.
Talks are under way about removing emergency care from hospitals in London, Surrey, Sussex, Greater Manchester, Lancashire and Cornwall.
The sites will either close or be left to handle basic care, with "super" regional centres seeing the most ill.
NHS bosses say the measures are aimed at reducing deficits and treating more patients in the community.
But there are concerns people will have to travel miles for life-saving treatment.
George Beer, of the British Cardiac Patients Association, who is campaigning against changes to hospital services in Sussex, said: "If services are closed, severely ill patients will have to travel miles for care. It is putting lives at risk."
Further evidence of the move to centralised services at certain hospitals will emerge on Friday with the unveiling of six new PFI schemes.
The projects, worth a combined £1.5bn, include expanding A&E facilities in hospitals in Salford and Leicester and building a cancer centre in north Staffordshire.
The schemes do not cover any of the trusts identified in the BBC News investigation.
Some of the options being drawn up by those trusts which are looking to cut services involve transferring all acute care - accident and emergency departments, heart care units and critical care beds - to nearby hospitals to create regional "super" centres.
The other hospitals in the area will then be left to carry out more basic care, such as non-emergency surgery, diagnostics and rehabilitation care, such as physiotherapy.
But in some cases, whole hospital closures are being considered.
Over 30 hospitals could be affected by the reviews - including those losing services and others left to bear the brunt of that work.
It is thought about 10 of these could face cuts or closures.
The areas under review are:
- London - Talks under way over Harrow's Northwick Park and the nearby Central Middlesex hospitals
- Project board set up to review services across the four north central trusts - Barnet and Chase Farm, Royal Free, Whittington and North Middlesex
- Surrey and Sussex - Widespread discussions have been followed by the creation of focus groups to discuss future of the 15 hospitals run by nine NHS trusts. Formal consultation to start in the autumn
- Greater Manchester - Committee set up to decide the future of four hospitals run by the Pennine Acute Hospitals NHS Trust. Decision due end of September
- Lancashire - Changes to the University Hospitals of Morecambe Bay Trust's three centres - spread across Cumbria and Lancashire, planned, with the Westmorland threatened with losing its acute facilities
- Cornwall - Two proposals have been discussed by Royal Cornwall Hospitals NHS Trust, one of which involves withdrawing services from two of its three hospitals
NHS bosses involved in the reviews have said the measures are part of a push to provide more care in the community, either with hospital doctors setting up local clinics, GPs providing extra specialist services or medics treating patients in their own homes.
However, they also acknowledge deficits and new European working time restrictions are forcing them to reconsider how services are provided.
All the hospitals in Surrey and Sussex, which is overspending by £100m a year, are under review, while talks are in the early stages over five north London trusts and the Royal Cornwall Hospitals Trust.
A consultation has already been launched in Morecambe Bay to decide over the future of three local hospitals - the Westmorland could lose acute services as part of the review.
But a decision is closest on the four hospitals run by the Pennine Acute Hospitals Trust, which is facing a £21m deficit this year, with a committee of local health bosses expected to make an announcement by the end of September.
Three options were consulted on, ranging from keeping three acute hospitals to just one, with the remainder becoming "locality hospitals" providing planned surgery and intermediate care.
There are 175 acute hospital trusts in England -and it is possible that more areas will see hospitals downgraded or closed.
Government ministers are said to be privately bracing themselves for major hospitals to be affected in the coming months as part of the continued pressure on the health service from deficits - the NHS finished last year over £500m in debt.
But, in an official statement, a Department of Health spokesman said it was up to local health bosses to decide on the appropriate level of services.
"In some areas, there are too many hospitals providing the same or similar services which isn't value for money and means less resources for other forms of health care."
Nigel Edwards, director of policy at the NHS Confederation, which represents health trusts, said: "One of the reasons trusts are running up deficits is that these decisions were not made earlier. It makes sense to do more care in the community for clinical and financial reasons."
But he said he was concerned acute care could end up centralised in too few hospitals.
Dr Jonathan Fielden, deputy chairman of the British Medical Association's consultants committee, added: "In some of these cases we have to ask whether this is being driven by financial reasons.
"If this is the case, it is likely not to be in the best interests of patients."