A £100billion forest city eco-plan for 400,000 new homes has been branded a 'state-subsidised concrete sprawl'.

The project would span 45,000 acres of farmland on the border of Suffolk and Cambridgeshire, incorporating England's biggest nature reserve as well as a large reservoir.

Sir Tim Smit, co-founder of the Eden Project, has insisted it is in the 'national interest' for the proposals to go ahead.

But Nick Timothy, Conservative MP for West Suffolk, said the city would not be an 'eco-friendly utopia' - rather, a 'dystopian, state-subsidised concrete sprawl'.

In the foreword to a report submitted by the Ministry of Housing, Communities and Local Government, Sir Tim said this week: '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.'

The plans, dubbed Forest City 1, are now awaiting the opinion of Labour Housing Secretary Steve Reed.

They are being sold as an alternative to the Government's plans for Greater Cambridge - which would realise chancellor Rachel Reeves' vision to turn the area into Europe's own Silicon Valley-style development.

It comes as the government proposals have already been rejected by city and district councillors.

Supporters say Forest City 1, east of Cambridge, would offer a creative solution to Britain's 'national housing crisis' and help kick-start growth.

Around 12,000 acres of forests, wetlands and woodland would be delivered as part of the project, along with 8,000 acres of space for offices, shops and other commercial uses.

The nature reserve would be home to wildlife including beavers, storks, lynxes and wild boar, it is envisaged.

Jackie Sadek, a former specialist adviser to the Government on urban regeneration, previously called the plans 'not credible'.

Though, despite the hesitant comment, one of the plan designers confirmed to the Daily Mail that Ms Sadek is now on the project advisory board. 

Among the project's supporters are former trade and industry secretary Dame Patricia Hewitt and Professor Tim Leunig - former adviser to two Conservative chancellors and three housing secretaries.

The plans have been drawn up by entrepreneurs Shiv Malik and Joe Reeve.

Financial details of the project are yet to be formally submitted but Mr Malik previously touted a cost figure of 'easily over £100billion'.

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.'

It adds: 'We think it’s time to be far more ambitious. Let’s fight for a grander vision. Something far more tangible than abstract, wonkish, rule changes. Let’s fight for a project, and a vision which a broader collective can get behind.'