Nearly 500 protesters rallied against controversial plans to build hundreds of new homes on green fields on the edge of the South Downs National Park.
Developers want to build up to 100 houses between Ovingdean and Woodingdean, with plans expected to go to Brighton and Hove City Council within weeks.
But the proposals have caused uproar in neighbouring villages and on Thursday evening hundreds attended a rally to voice their concerns, organised by members of the Save Our Deans campaign.
Speakers included MP Simon Kirby, who said he was willing to take the fight to the Government if the council failed to block the plans.
He told the crowd: “If the council in Brighton and Hove don’t see sense I will approach the Secretary of State and I will ask for the planning application to be called in and press the case of how important this is.”
Rottingdean councillor Mary Mears said she was concerned failure to block the proposals could cause a precedent for future developments on green fields.
She said: “This site is so important.
It is the one that has to be stopped. By stopping this one we protect the other areas.
“It’s really important everyone gets behind this campaign. If we don’t and this gets through we’ll have great difficulty stopping everything else.”
Last year Brighton and Hove City Council was criticized by the Government after drawing up plans for 11,300 homes – thousands belowthe expected demand of 20,000.
An online petition has already gathered 195 supporters, and campaigners were busy collecting signatures during the event at Longhill School.
Labour’s parliamentary candidate for the area, Nancy Platts, said councils were being forced to find in favour of developers while the Green’s candidate Davey Jones said the National Planning Policy Framework – which requires councils to identify green spaces for development – was a major reason for concern.
Those who live close to the development said they were concerned about the strain so many new houses could have on the local amenities and infrastructure.
Resident Neville Stott said: “It’s already limited here and if we’re going to have a full lump of houses from the Downs to the seafront it’s going to take away the green areas.”
David Johnson from the Sussex Campaign to Protect Rural England, added: “It’s going to be a campaign that needs to go on and on because it’s a valuable site.”
Ken Parker, who lives close to the site, added: “There’s a big concern in the local area with urban sprawl.”