Neighbours have accused a property developer of bulldozing a nature reserve which was a "green oasis" among a sea of new homes.
People living in Southdown Road, Newhaven, stopped diggers crashing through the last section of a strip of green land which Hampshire-based developers Westbury Homes pledged to keep for wildlife.
But residents say almost all of the grassland, trees and hedges - a haven for badgers, field mice, newts and birds - was destroyed.
The strip also provided a barrier between houses in Southdown Road and the development of 140 homes at Harbour Heights, close to Tideway School.
Westbury Homes is investigating.
But local people say it is too late.
Plans approved by Lewes District Council show a 3m strip of land should have been left undeveloped.
A spokesman for the council said: "We are investigating the concerns raised by residents."
Stanley Hart, 79, of Southdown Road, who has lived there for 51 years said: "We were assured the strip of land along the back of Southdown Road would be kept as a wildlife area. We regard it as our nature reserve.
"It was home to newts, lizards and grass snakes as well as birds and other small animals. Some came running out as the digger went through.
"I asked the workmen what they were doing and they said they were clearing the land to make a path."
Graham Amy, 56, chairman of Southdown Badger Protection Group said: "There is evidence of badgers foraging in the area as well as other wildlife.
"We were promised by Westbury Homes it would leave it as an area for wildlife and if there was any need to work in the area it would do it by hand."
Newhaven town and county councillor David Rogers said: "It has always been agreed this strip of land should be left for wildlife and all plans show this. I share the residents' concern."
Donna Saunders, 31, of Southdown Road said: "We are all furious and have signed a petition condemning this destruction and demanding reinstatement, even though it is too late."
Bryan Leeming, regional technical director for Westbury Homes, said: "We are aware of the situation and are currently carrying out an investigation.
"We are making every effort to retain those boundaries between the two developments for the security of all concerned.
"We are currently liaising with both our own consultants and the council's advisers in matters of ecology."
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article