A GP group has described the possibility of closing key services at Croydon University Hospital as "crackpot" and "undeliverable".
Shutting the hospital's emergency, maternity and children's units is one of three options put forward by a controversial review of healthcare in south west London.
Downgrading the hospital is the least preferred choice of the Better Service, Better Value (BSBV) reforms.
Speaking at a public meeting of the governing body on Tuesday, a number of Croydon Clinical Commission Group (CCG) board members questioned why it has been suggested at all.
David Hughes, a lay member of the board, said the plan would have a serious impact on trusts in south east London.
He said: "King's College Hospital (in Camberwell) would have to cope with a lot of the A&E patients who are currently coming to Croydon.
"They expressed concern that they already have insufficient number of beds, a situation which is likely to be exacerbated.
"There's a very real concern that option three isn't actually deliverable because south east London would have a great deal of difficulty coping with the number of A&E patients that Croydon generates."
Hannah Miller, board member and executive director of adult services and health at Croydon Council, said: "I can't see any evidence that any broad perspectives have been taken into consideration in putting the third option forward.
"If Croydon were a city we would be the sixth largest population in the country. We're planning under the Local Development Plan to have another 20,000 new homes in Croydon in the next decade or so.
"The idea that someone could put forward such a crackpot option for a city the size of Croydon to have a culled hospital site I think beggars belief."
Option three would see St Helier, in Sutton, remain as a major acute hospital with Croydon downgraded, leading to increased travel times for emergency and maternity care affecting around 250,000 people.
It is also the most expensive of the options, requiring a capital outlay of £442 million, of which the cost of redeveloping King's, including purchasing land in Brixton, would represent £137m.
The BSBV board have agreed to review the option following "serious concerns" raised by the hospital.
However, Rachel Tyndall, senior responsible officer for BSBV, defended the inclusion of closing services in Croydon because "clinically, it delivers the benefits".
"In our methodology we were impartial," she told the meeting at Croydon & District Masonic Hall in Oakfield Road, West Croydon.
"We looked at all five hospitals evenly. We had a set of criteria, non-financial and financial, on which they were assessed.
"Out of that process the option where Croydon should be a local hospital remained on the table.
"The view of the programme board is that it is a high risk option and is the least preferred of the three that have been put forward.
"Given the concerns about deliverability which have been discussed by the programme board, and the comments from King's, we have agreed to do more work.
"The last thing we should be doing, should the results of consultation favour that option, is to pursue something which actually turns out not to work well and isn't in the best interests of patients."
The BSBV review covers Croydon, Kingston, St George's in Tooting, St Helier and Epsom hospitals.
It aims to cut costs and drive up standards, increasing consultant cover at A&E and maternity units in the face of staff shortages by centralising those services at three expanded hospitals.
The preferred option would see Croydon remain as one of the major acute sites, with £75 million of investment in order to cope with the additional pressure, including a 24 per cent increase in births, as a result of downgrading St Helier.
A joint committee of the region's seven CCGs will decide whether the three options should go out to public consultation in June.
Dr Brzezicki said: "None of the CCGs believe the no change option is practical. We would be unable to improve quality and safety, and indeed quality would likely go down.
"Option three has the greatest impact on patients and families and will increase traveling times for about half a million people and will have a disproportionate impact on the most populous and deprived area of south west London."
John Goulston, chief executive of Croydon Health Services, the trust which runs the hospital, said:"It is extremely good news for Croydon that the CCG is supportive of these proposed options.
"The hospital is included in two of these as a major site, with A&E and maternity services.
"Croydon is one of the most densely populated places in London - people should have access to a hospital with the staff and services to treat them when they need it most."
