A think tank's idea for one million new homes in Oxford was yesterday dubbed "a vision of hell".

Policy Exchange, which has close links to the Conservative Party, unveiled the idea as it argued Oxford, Cambridge and London should take a million homes each because it was not worth regenerating northern cities.

It is estimated their plan would swell Oxford's population to about 2.5 million, the equivalent of the metropolitan area of the West Midlands.

On current housing densities, an area matching that would see 'Oxford' sprawl across the county east to west from the M40 to past Witney and north and south from Bicester to Abingdon.

Oxfordshire County Council leader Keith Mitchell yesterday called the report "madness" and questioned what effects such migration would have on local infrastructure.

Mr Mitchell, who is also chairman of the South East England Regional Assembly, said: "If this were to happen, people in Oxford would react with complete horror. This report has no merits at all. It would mean concreting over Oxford.

"We would become another borough of London and that isn't what makes Oxfordshire an attractive place to live and work. It's just madness.

"It would bring complete gridlock. The spaces where building can take place in Oxford are limited and the transport network by road and rail is at capacity at the moment. We need some growth, but it needs to be planned and managed properly."

The report argued that house-building restrictions in the South East should be lifted to lower house prices and stop people on low incomes being trapped in less prosperous parts of the country.

It also claimed an expanded Oxford would be richer than anywhere else in Britain, outside London.

But Oxford City Council's deputy leader Ed Turner, board member for strategic development, said: "This report is completely barking. We have an enormous need for housing in Oxford, but this is complete nonsense. It is never going to happen."

The plans were also blasted by Norman Machin, the joint-chairman of the Weston Front campaign group fighting plans for a 15,000-home eco-town close to Bicester.

He said: "This would be a vision of hell. Where on earth do they think they will put all these homes?"

Tory leader and Witney MP David Cameron said: "The authors of this report have themselves admitted it is barmy. It isn't, it is insane."

The think tank has worked on the scheme for a year and co-author Tim Leunig, who spent several years in the city as a student, said he meant for his recommendations to be taken seriously - although he admitted "some people will claim that these proposals are unworkable, unreason- able and perhaps plain barmy".

He said: "The Government has run out of money and regeneration funding is unlikely to go up in future. Many cities in the North are going to struggle."

Noting the negative response of some in the city so far, he joked: "You can never tell what the reaction will be, but I wasnt expecting people to be rushing to put up statues of me.

OVER the next 20 years the South East Development Plan has called for 662,500 homes to be built across the region, with 55,200 homes set aside for Oxfordshire. Of that, Oxford city has been told to provide 8,000 new homes with an additional 4,000 homes south of Oxford recently earmarked on land south of Grenoble Road.

There has been a long history of disputes between the city, district and county councils over plans for more houses in the county and the desire to expand Oxford beyond its current boundaries. The city's Labour administration has backed plans for the 15,000-home settlement Weston Otmoor "eco town", while the county council has officially voiced its concerns.