Hundreds of new homes could be built on empty land at the foot of a national park.
Campaigners in Ferring and Goring, near Worthing, believe developers want to build 396 new houses on land separating the two settlements south of Highdown Hill.
Campaigners say the land, locally known as southern and northern Goring Gap, has been subject to soil samples by consultants working for developers Persimmon Homes.
No application has been made for development on the site, but people are calling on the firm to announce its intentions.
Ed Miller, of the Goring Gap Action Group, said: “It’s obvious from all the work which has been going on, and the drawing produced by planning consultants WYG showing 396 houses to be built in the northern section of the Gap, that there is a serious intention to seek planning permission for a very large development.
“Persimmon Homes must explain to Ferring and Goring residents just what they intend to do.”
Mr Miller said members of Ferring Conservation Group were collecting evidence on the wildlife and landscape value of the land in a bid to have it designated a site of nature conservation importance.
He said: “Residents value the Ferring-Goring Gap very highly - as an important visual break in the built-up area along the coast, as an important area for wildlife, as a 'green lung', and as Grade A agricultural land.
xhyead “The view from the beach, over the fields and across the avenue of Ilex Oaks, up to Highdown Hill and the South Downs National Park, is one of the most beautiful on the Sussex coastal plain. We must not let it be filled with houses.”
Paul Bedford, senior land and planning manager for Persimmon Homes South Coast, said the land was suitable for development.
He said: “Last year, Worthing Borough Council issued a ‘call for sites’ to all landowners, including ourselves, and in response we decided to undertake a topographical survey of the area so that we had an accurate record of our land holding.
“We responded to the call for sites by the council and confirmed our long held position that, in our opinion, the site is both available and suitable for development if needed.
“If Persimmon does decide that the need for housing is such that an application is appropriate we will hold an exhibition so that the local community will be aware of what is being considered and have the opportunity to comment.”
A public meeting organised by Ferring Parish Council is being held at the Glebelands Centre in Greystoke Road, Ferring, at 7pm on April 22 to address concerns about the potential development.
A spokesman from Persimmon Homes confirmed it had accepted an invitation to attend.