Edward Agombar, 11, in campaign to save Winchester's River Park
An 11-year-old boy from Winchester has started a campaign to protect his local park from potentially being built on.
Schoolboy Edward Agombar said he was "shocked" to hear some of River Park's land could be used in plans to expand the existing leisure centre on site.
He said the park was "where I often climb trees and play outside with my friends".
Winchester City Council said its plans on public display showed "the recreation ground is not under threat".
The council claims the present leisure centre has "increasingly deteriorating facilities" and is holding a public consultation featuring four options until 2 December.
Edward's Save The Rec campaign voices concerns the council could approve option two: to build a larger centre in what is the city's only major park.
A report commissioned by the council stated option two "would occupy most of the area of the existing pitch, resulting in a complete change in character of this part of the site from open recreation ground to built development".
Edward said: "I am really worried that there will be hardly any green areas left in Winchester soon".
He created a website which has led to 350 people signing up to be part of the campaign.
A council spokesman said none of the options "required anyone to 'save the rec' because the recreation ground is not under threat".
However, campaigners insisted two of the four options being considered by the council involved building on some portion of the park.
Campaign spokesperson James McConnachie said the public display was "inadequate" because it showed no confirmation of how much land the larger centre would use, no plans for access roads and no indication of building height.
He said: "This is Winchester's only park - if New York can keep Central Park we should be able to keep ours".
Save The Rec is holding an open meeting at Winchester Rugby Club on Monday.