Sir William Prob complained that planning decisions were being driven by "narrow economic objectives" amid suggestions the organisation could seek to actively block developments.

But his claims were dismissed by the Government which said the extra homes needed to ease the present shortage could be built while protecting the environment and green belt.

Prime Minister Gordon Brown has pledged to build 240,000 homes a year by 2016, three million extra between now and 2020, in a bid to ease pressure and stop first-time buyers being priced out of the market. Last week an independent advisory body said that figure would have to rise further still.

Sir William, who is due to address the annual meeting of the trust, said the house building policy was proceeding like a "juggernaut".

He told The Times: "In the planning process I am not sure the value of the spiritual side and the beauty of landscape and its importance on the quality of life rather than the financial gain is taken into account.

"It should do that but I feel the process is being driven by economic arguments from a top-down planning process. Development is being pushed through; the process is being driven by narrow economic objectives and once we've lost these green spaces they have gone forever and there is no turning back."

A spokesman for the Department for Communities and Local Government said: "These claims are flawed and misunderstand the planning protections that are in place to safeguard the countryside and open green space.

"The priority put on brownfield development has substantially increased protection for the countryside, with 74% of all new housing currently being built on recycled land, up from 57% in 1997.

"Over the same period, we have seen the amount of green belt land increase by 64 thousand acres. For the sake of first time buyers and families on council waiting lists, there is a need to build more homes but we believe it is possible to do so whilst protecting the environment and green spaces."