Plans to build a new stadium for Oxford United on greenbelt land must be "kicked out", campaigners have said.
Leader of Oxfordshire County Council Ian Hudspeth has advocated the U's move from Kassam Stadium to a site at Water Eaton despite his council not being the planning authority.
The local branch of the Campaign to Protect Rural England (CPRE) said the development would be "unacceptable".
But the U's supporters' trust said there was justification for the plan.
Oxford United fan Mr Hudspeth said it was vital the U's could get their own freehold stadium rather than their current position of having to pay rent for the Kassam.
He added: "Water Eaton, with the new [train] station opening next year, is going to be a fantastic transport link.
"It is in the greenbelt and I understand the sensitivities around that and we would have to work with Cherwell District Council to see if they could make an exception in this case."
The U's supporters' trust OxVox and Oxford City Stars ice hockey team, who hope a new arena could be built next to any new ground, support the move.
Mark Sennett, chairman of OxVox, said: "There's already extensive development going on at the Water Eaton site. I understand their concerns and they have to be taken seriously.
"We think it's a great opportunity. It would regenerate that part of Oxfordshire... it would also potentially allow Oxford City Council to meet their desperate need for housing."
But Oxfordshire CPRE said: "A commercial multi-seater stadium, with parking and other facilities, is development on an industrial scale and completely unacceptable.
"It is surprising that Councillor Hudspeth should be putting forward such a scheme, which is contrary to government policy, without any authority. We hope that other Oxford United fans will help us quickly kick out this idea."
A spokesman for Cherwell District Council said: "The land is classified as a greenbelt area which Cherwell is keen to retain."
The club is currently the subject of multiple takeover bids.