A decision on plans to build more than 2,000 homes on a former airfield in Surrey has been delayed.
Wisley Property Investments is hoping to build homes, shops, a school, health centre and sports pitch on the former Wisley Airfield site.
A decision was expected by 24 December but Guildford councillor Tony Rooth said more information was needed.
However, Guildford greenbelt councillor Susan Parker fears the delay will play into the developer's hands.
Ms Parker, leader of the Guildford Greenbelt Group, said the decision could be taken away from the borough if it doesn't come to a decision by the agreed date.
She explained: "The applicant could seek to go to the inspector on the grounds of non-determination which means the council hasn't decided therefore you have to decide Mr Inspector.
"And the inspector normally has more of the presumption in favour of approving something if there has been non-determination."
But Guildford's lead councillor on housing Tony Rooth said it was a very big project with "all sorts of issues" which would take a long time to evaluate.
He added: "What we need are brownfield sites where much-needed housing in Guildford can be built.
"Whether Wisley qualifies as a brownfield, or even a white concrete site as opposed to a Greenbelt site, we will evaluate when the applications are fully ready to consider."
Guildford Borough Council confirmed the 24 December date was "now unlikely" and said it would be seeking to agree a further extension of time.