The report, published on Tuesday (September 12) by The King's Fund and Nuffield Trust, was prepared by leading health experts and “casts serious doubts” on NHS proposals.
It suggests that, in order to keep up with current demand, as many as 1,700 extra acute beds could be needed in the capital by 2012.
The health experts' findings come as NHS North West London considers plans to remove services from the Uxbridge Road hospital.
According to Ealing Council, this will result in the hospital's blue-light A&E unit being closed and an 80% reduction in beds.
The King's Fund and Nuffield Trust's report suggests that the level of bed occupancy, which is running at 90% in the capital, is too high if hospitals are to be run “smoothly and safely”.
On top of that, NHS assumptions about how it will reduce hospital capacity in the region are “not always clear”, according to the health experts.
The report's authors also claim it would require “a heroic effort by all parts of the health and care system” to reduce the numbers of people going to hospital by 2021.
In their view, experts said that this reduction is “highly unlikely to be achievable” over this period.
'We don't believe these plans are safe'
Ealing Council leader Julian Bell, said: “This report, prepared by the country’s leading health experts, vindicates everything we have been saying since these ill-conceived plans were first presented.
“We don’t believe these plans are safe, there is not the capacity elsewhere in the system and the speed and scale of change is unrealistic.
“A&E waiting times in north-west London are already amongst the worst in the country. Ealing’s population is growing and the pressures on the local NHS are already acute, stripping away vital services and capacity is nonsensical.”
Ealing Hospital had its maternity services taken away in July 2015 and a decision to close the blue-light A&E services at the hospital is also expected next year.
While there will be a GP-run Urgent Care Centre at Ealing Hospital, residents could face at least a 40-minute journey on public transport to their nearest A&E department.
'I know our residents are not being given the whole picture'
“I want to see an immediate halt of the plans in north-west London so people can be assured that they and their loved ones will get the care they need in an emergency,” Councillor Bell added.
“I welcome the Mayor of London’s proposal to work with the NHS to provide greater scrutiny over what is proposed to ensure that Londoners feel safe and will get the health services they need.
“The NHS needs to build trust with Londoners and to be clear about what is proposed and listen to residents’ views. I know in Ealing our residents are not being given the whole picture.”
A spokesman from the North West London collaboration of clinical commissioning groups said: "Over the next few years we will be looking at where we can best provide services for residents, including GP practices, the community and hospital.
"New services will be developed and some existing services will change.
"No changes will be made until new community services are up and running and will talk to residents.”
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