Hundreds of homes could be built on protected greenfield sites in the South Downs because of the new national park, it has been claimed.

East Sussex County Council leader Peter Jones accused the Government of using the national park to impose more house building.

He said land in the existing Sussex Downs area of outstanding natural beauty (AONB) that was not included in the new park would be a magnet for developers.

The Countryside Agency expects to agree to remove parts of the AONB next month, when they meet to consider the finalised park proposals.

Coun Jones said: "If they do de-designate the rest of the AONB, then the Government will use that to put pressure on us to build houses on vast tracts of our precious countryside.

"The concreting over of this beautiful county is one of the consequences of a national park being imposed on it.

"It is something we have got to be aware of."

The agency wants to de-designate 53 pockets of land outside the new park's boundaries, totalling about 9sqkm, in East and West Sussex.

About 2,000 homes are usually built per square kilometre. Some of the pockets of land due to be de-designated are unsuitable for building while other have already been built on.

The council, which is among the bitterest opponents of a national park, has already said it does not want areas such as cliff tops at Telscombe Cliffs, the University of Sussex's campus or Village Way North - the site of the Albion's proposed stadium - de-designated.

Labour county councillor Keith Bridger accused Coun Jones of "scaremongering" and said he opposed the park because the Conservatives represented a "very privileged minority with vested interests".

He said: "It is absolute rubbish. One wonders where he will stop in trying to make another political point."

Prominent national park campaigner Paul Millmore said councils would be responsible for protecting the sites in the same way as other land on the fringes of the existing AONB.

He said: "De-designation does not mean they are going to be automatically developed."

The national park is not expected to be operational until 2006 or 2007.