A proposed £100 billion "eco-city" development that would create 400,000 homes has been branded a "dystopian concrete sprawl".
The Forest City project would cover 45,000 acres of agricultural land straddling the Suffolk and Cambridgeshire border.
Plans include what would become England's largest nature reserve alongside a major reservoir.
Sir Tim Smit, who co-founded the Eden Project, has come out to back the scheme.
But top Tory Nick Timothy, the MP for West Suffolk, has attacked the proposal.
He said the city would not be an "eco-friendly utopia" but rather a "dystopian, state-subsidised concrete sprawl".
West Suffolk district councillor Joe Mason also issued a dire development warning.
"I don't think I can say it loudly enough: West Suffolk is not empty space on a map waiting to be redesigned.
"It is a network of villages and landscapes that have developed over centuries.
"Communities such as Withersfield, Cowlinge, Great Bradley and the Thurlows would all find themselves directly affected by something on this scale."
Ancient English farmland would be redeveloped into 'Forest City' under the plans
|FOREST CITY 1
Either way, Housing Secretary Steve Reed is now considering the ambitious eco-plans.
Sir Tim wrote the foreword to a report submitted to Mr Reed's Ministry of Housing, Communities and Local Government this week.
In it, he said: "It is in the national interest that we put our faith in people and organisations that believe that the future remains ours to make.
"All across the country people are listless in the face of inertia. Forest City provides a creative spark, an imaginative leap and a roadmap for a beautiful future with a new way to live.
"How much better to aim for something that a century from now will have people thankful we were here at this moment, than held transfixed in aspic by an imagined glorious past."
BRITAIN'S COUNTRYSIDE UNDER THREAT? READ MORE:
- Labour plan to turn 500,000 acres of countryside into Net Zero farms condemned by Reform UK and farmers
- Travellers bulldoze and concrete green belt land over Easter weekend 'in hope local council will be too slow to react'
- Labour draws up plans to make Britain's countryside 'less white' in nationwide diversity drive
Shadow Justice Secretary Nick Timothy warned the plans would represent a 'dystopian, state-subsidised concrete sprawl'
| HOUSE OF COMMONSThe development would sit east of Cambridge and is being presented as an alternative to the Government's Greater Cambridge proposals.
Labour's plans - under the Chancellor's push to create a European Silicon Valley - have already been rejected by local councillors.
Backers argue Forest City 1 offers a creative answer to Britain's housing crisis while stimulating economic growth.
The scheme would deliver approximately 12,000 acres of forests, wetlands and woodland.
A further 8,000 acres would be set aside for offices, shops and other commercial premises.
Some 8,000 acres of greenery would be set aside for offices, shops and other commercial premises
|GETTY
The planned nature reserve would house beavers, storks, lynxes and wild boar.
Entrepreneurs Shiv Malik and Joe Reeve drew up the plans.
Mr Malik has previously suggested the project would cost "easily over £100billion", though formal financial details have not yet been submitted.
The scheme has attracted notable supporters including former Trade Secretary Dame Patricia Hewitt and Professor Tim Leunig, who advised two Tory chancellors and three housing secretaries.
Jackie Sadek, a former Government adviser on urban regeneration, initially called the plans "not credible" - but has since joined the project's advisory board.
A planning statement reads: "After 15 years of stagnation, we need to unlock huge growth and prove to ourselves and the world Britain can still build extraordinary things that inspire the world."