Residents in Peacehaven are furious at plans to hand their last open recreation space to a school that wants to build on it.
They feel they are being ignored in favour of pupils over the future for Joff Field.
The residents are objecting after the plans were revealed just weeks after they were told they would no longer be able to use the community leisure centre on weekdays from September because it was being commandeered by the school for sports lessons.
In the latest development, East Sussex County Council wants to build on Joff Field to provide school offices, storage areas, changing rooms and six tennis hard courts and football pitches.
The authority wants to fence the area off for the exclusive use by pupils of the recently-built £30 million Peacehaven Community School.
The protesters say the field is the last recreation space in the town and should not be handed to the school. There is also a public right of way across the area which residents say should be maintained.
John Hodgson of Capel Avenue, Peacehaven, has lived in the town for 26 years.
He said: "I recognise the need for additional facilities for the school but the Joff Field is a gem. It is a central and well-used piece of recreational land in the heart of a town with the second highest shortfall in recreational land in the Lewes district."
More than 300 leaflets have been sent to homes in the area asking residents to object to the plans.
Tony Payne, the first mayor of Peacehaven, said: "We had so much land when I came here in 1951 it was almost an embarrassment. If they use the field we will have none. It has all been nibbled away."
More than 500 residents have signed the petition so far and residents are asking for Peacehaven Town Council to make a formal objection to the county council by February 27.
A spokesman for the county council said: "Far from being to the detriment of the local community, these all-weather facilities will enhance what is available as they will be available for hire at evenings and weekends."
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