Charities say Arc plan is 'perfect opportunity' to invest in nature
Conservation charities have said a project which includes building up to one million new homes is a "perfect opportunity to invest in nature".
The government wants to build them in the Oxford-Cambridge Arc by 2050 to make the region "an economic asset of international standing".
Environmentalists have previously argued the mega-plan will ruin green space the size of Birmingham.
A plan for a new expressway between the university cities is under review.
The RSPB and Berkshire, Buckinghamshire and Oxfordshire Wildlife Trust (BBOWT) said the Arc was already "one of the most nature-deprived parts of the country", despite the region retaining "important wildlife-rich sites".
They were joined in their calls by the Wildlife Trust for Bedfordshire, Cambridgeshire and Northamptonshire (BCNWT) and the Woodland Trust.
The charities said any new developments built in the Arc must be zero-carbon and that "all local decision makers" should "put nature at the heart of development to achieve a net gain for wildlife".
What is the Oxford-Cambridge Arc?
•One million homes built between Oxford and Cambridge by 2050 to support existing and new jobs
•The government approved the project after it was proposed by the National Infrastructure Commission in 2017
•The charities say the Arc "presents an opportunity to put nature first so that development can be delivered without damaging nature and the environment".
•They want new places in it to enable residents to "benefit from a thriving natural environment that supports healthy and sustainable lifestyles."
Jeff Knott, the RSPB's operations director for Central England, said: "The importance of nature during the coronavirus crisis and support for a green recovery have made the need for growth and development to help restore nature clearer than ever. This is a huge opportunity to do things differently.
"For the Oxford-Cambridge Arc to play its part in a green recovery it needs to have world leading ambitions to increase nature that match and underpin its aspirations for economic growth."
But journalist George Monbiot, who lives in Oxford, accused the charities of "selling out".
He claimed they were "collaborating with the very forces they should be opposing" and added: "With friends like these, who needs enemies?"