Workmen were spotted testing the ground at Bowlands Hey just days after Bellway had plans for 129 houses rejected.
The fields off The Fairways are part of a plan to build a 1,000 house mega estate which would extend as far as Dobb Brow and Green Meadows.
The proposal, submitted after a call by Labour-run Bolton Council for more housing, would see Westhoughton’s last-remaining green fields concreted over.
Last week Bellway Homes were refused permission to build houses off Collingwood Way but it is now thought that they are turning their attentions to the larger development as outlined in the Greater Manchester Spatial Framework.
Westhoughton town councillor David Wilkinson said: “Residents were quite rightly concerned to see workmen carrying out tests on the site this week.
“Sadly these fields are being eyed up by developers because this Labour-run council asked them to come forward with suggested sites.”