Families are angry that plans to develop an area of communal land have been passed behind closed doors.
Oxford City Council officers have approved plans to build three houses on a site that borders Cavendish Drive, Fane Road and Salford Road in Old Marston.
However, a group of 21 householders in Salford Road and Cavendish Drive say their property deeds give them rights over the land, which is used for parking and as a play area for children.
Salford Road resident June Westbury said the council failed to inform people about the scheme by putting up a planning notice. Residents have now asked a solicitor to find out what rights they may have over the land.
Sally Thomas, who owns a property in Fane Road, said: "Marston is a community where we want our children to have open space to play.
"The paved area has always been used by children after school and for parking in the evening. The minute you have on-street parking, crossing the road becomes dangerous for children."
Council officers have the power to decide applications for developments with up to five houses, but four councillors can ask for controversial plans to be decided at an area committee meeting.
Cllr Jock Coats said: "What we need to establish now is whether the residents have any rights over the land to prevent someone developing it.
"I will be asking the council's property officers whether they have a right to adopt the land as no-one had come forward to claim ownership of it for such a long period."
He said the owner only became aware the land was his when residents tried to find out if the council could provide play equipment.
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