Final decision to be made on eco-town plans
But she signalled she would be willing to block every planned eco-town if her tough environmental standards are not met.
Raising the prospect of the flagship project being abandoned entirely, Mrs Beckett said progress had stalled after a series of legal challenges.
Developer Imerys is proposing to develop six former clay mines in the St Austell area as part of Gordon Brown's pledge to build up to 10 new eco-towns.
The proposal includes building more than 5,000 homes between 2012 and 2025, as well as the creation of office space and schools.
Around 40 to 50%of the homes will be affordable in a bid to tackle Cornwall's housing shortage.
A panel of experts appointed by ministers last year called for the developers to step up their efforts to ensure the plans would create ultra-green communities.
It included looking again at the plan to offer charge-points for electric cars, something that Imerys is looking into.
The whole process has been delayed by critics of one of the schemes elsewhere in the country who have taken their opposition to the courts.
Mrs Beckett said she did not regret the way the policy has been handled despite it being shrouded in controversy and several proposals already being dropped.
She denied the scheme had been put on the back burner, but said the assessment of proposed schemes had been slowed down by the high court battle over claims there had been a lack of consultation.
Proposals
Mrs Beckett said: "There are some proposals that have been judged to be unlikely to be able to reach the standards we demand given their present form, but there's a silver lining to that cloud – it does show it's not just a matter of putting forward a set of proposals and sticking a label eco-town on them.
"If no proposals meet the environmental standards there will not be any names coming forward, though I would be very disappointed and somewhat surprised if that were to be the case."
In March it emerged the taxpayer could be forced to plug a £190 million funding gap in the St Austell bid.
Government advisers said the scheme planned would need 'substantial levels of public subsidy' in order to go ahead.
Families might not move into the 5,000 homes until 2030 and the total cost over 30 years could reach £1.2 billion at today's prices.
The availability of funding remained a 'key risk' to the future of the project, PricewaterhouseCoopers said in the document titled 'financial viability study of the eco-towns programme' that funding could be an issue.
The report also warned the timescale is 'very ambitious' and suggested the houses might not be ready until 2030.
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