Campaigners trying to save 100-year-old allotments have been told that they will be evicted next week.
The allotments are at the foot of the Rhigos mountain
Allotment holders have contacted police after a letter told them "bailiffs and appropriate security" would mean their "physical exclusion".
Those renting land at Haigside allotments in Treherbert, Rhondda, include pensioners and a riding school for disabled children.
Neither landowner Steven Evans nor his solicitor could be reached for comment.
Members of Haigside Allotment Society said Mr Evans's solicitor sent recorded delivery letters to them at the weekend informing them of the planned eviction on 14 March.
The society, which includes the holders of allotments and small holdings and the riding school, is opposed to the four-acre (1.6 hectare) site being considered for inclusion in the next local development plan.
They have drawn up a petition signed by 3,600 people calling on Rhondda Cynon Taf Council to protect the land, at the foot of the Rhigos mountain, for community use.
Allotment holders have drawn up a 3,600 signature petition
Treasurer John Evans said members were "distressed" by the solicitor's letter and had spoken to police about its reference to "security".
"We would welcome a police presence [on 14 March] because we've got a legal right to get on to these allotments."
Mr Evans said society members' animals included pigeons, dogs, geese and chickens as well as those at the riding school.
Rhondda MP Chris Bryant said the council should declare the land unsuitable for housing and keep it for allotment use.
Mr Bryant said: "I'm not sure the law will allow a change in use if there's not enough allotment land in the Rhondda."
BBC Wales contacted the office of Mr Evans's solicitor, but the solicitor was not available for comment.