More than 5,000 residents have signed a petition calling for more beds in the rebuilt Whipps Cross hospital.
Whipps Cross University Hospital in Leytonstone will receive £350 million from the Government over five years to fund the rebuild, one of six hospitals in the country to receive extra funding.
While there is so far no confirmation of the exact number of beds planned for the new hospital, it is understood there will be fewer than the 636 currently available.
A petition with 5,703 signatures was handed to the Department of Health and Social Care on February 14 by the Waltham Forest Save Our NHS group.
Campaigner Mary Burnett said: “There is a mantra that we do not need more beds because everything can be done in the community, which is outrageous actually.
“You can’t get an appointment with the GP because we do not have enough. Social services is on its knees and staff in social care are not nursing staff.
“What’s really concerning about this is when things go wrong in the hospital it gets picked up, but if an elderly person dies at home because they did not have the treatment they needed, the responsibility for it can become much more complex.
“We are doing everything we possibly can to ring all the alarm bells. We need a new hospital but if we get one with not enough beds, we will still have people waiting on trolleys to be admitted.”
Whipps Cross is one of five hospitals run by Barts Health NHS Trust and serves a population of close to 400,000 people, expected to grow by 10 per cent by 2029.
Ms Burnett added: “We are certainly not saying Barts is a bad board, far from it, they are operating in a really difficult environment.
“The NHS is not properly funded and the push towards privatisation is enormous. There is a cost shunt from the NHS onto local authorities.
“But the council have got a job to scrutinise the health plans and we would like to see them challenge them more than they are.”
A spokesperson for Whipps Cross Hospital said: “We continue to work with our local health and social care partners to develop our plans for a new hospital at Whipps Cross.
“Key to this will be ensuring the right services are put in place to best meet the future health needs of our population, across not just a new hospital but also the wider primary and community services around it.”
Waltham Forest Council and the Department of Health and Social Care did not respond to requests for comment.