Housing minister Caroline Flint says the proposed housing development near Weston-on- the-Green could create up to 5,000 affordable homes "at a stroke".
Defending her decision to put Weston Otmoor near Bicester on the eco-town shortlist, the minister said Oxfordshire needed to see a massive increase in affordable housing.
And she has urged residents to weigh the benefits of an eco-town against on-going expansion of existing settlements.
But campaigners fighting the scheme, near the A34-M40 junction, dismiss its claimed green credentials as Government spin.
With villagers stepping up their campaign against the planned new settlement, Ms Flint appealed to residents not to reject out of hand "a golden opportunity to develop a greener generation of housing".
She added: "Housing demand has outstrippped supply and irrespective of short term market conditions, this has pushed prices far beyond the reach of many people.
"But do we need more houses round here? The answer is clearly yes. Not only are there around 3,400 families on a waiting list for affordable housing in Cherwell - there are almost 4,000 in Oxford.
"But these local authorities have only been able to build around 330 affordable houses combined each year. This eco-town would provide between 3,000 and 5,000 new affordable homes."
"There are opportunities to build new homes in and around the edges of existing towns and villages, but alone can this be enough?
"Eco-towns do offer a golden opportunity to develop a greener generation of housing."
Norman Machin, of the Weston Front group which is fighting the scheme by developers Parkridge to build 15,000 homes on a 2,000 acre site, said: "The minister is trying to put a positive spin on what is a bad mistake by Government.
"The proposals would be nothing more than a dormitory settlement attracting commuters.
"Her claims that eco-towns are going through the regular planning process would be laughable, if this were a laughing matter."
Cherwell District Council leader Barry Wood said: "This is completely contrary to our local plan, which sees housing growth at Bicester and Banbury - not Weston Otmoor."
Oxford City Council backs the scheme.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article