Mole Valley District Council is consulting on plans to move boundaries to allow the building of up to 2,200 homes over the next 13 years.
The Campaign to Protect Rural England (CPRE) has now started a campaign called Save Surrey's Countryside.
The council said there was insufficient land available in built-up areas for new homes and other development.
Andy Smith, from the Surrey branch of the CPRE, said the group was concerned about development around places like Guildford, Reigate and Leatherhead.
"These areas have been built and built over the years," he said.
"All these towns have expanded to such an extent we have to say enough is enough."
Mole Valley District Council said it was is looking at green belt land around the area's towns and larger villages to see if there was potential for development.
John Northcott, the councillor responsible for planning, said: "This consultation document does not identify sites for development or suggest land that could be taken out of the green belt.
"Instead it sets out a process for reviewing the green belt boundary and we will use the findings of the consultation to help shape our future work."

Martin Hamilton said water used for washing crops on his land had leaked into the Enler River, near Comber.
He estimated about 25 tonnes, or 25,000 litres of the dirty water, which kills the oxygen in the river, left the farm.
Local people estimate thousands of fish had died. The Department of the Environment (DoE) said it was a water pollution incident of "high severity".
Two government departments are investigating.
Martin Hamilton told the BBC: "We have a massive run-off on one of the fields and we have got ourselves into a real mess. A total apology from ourselves to everyone involved."
He said not all of the dirty water had gone into the river.
"It is a situation that we are deeply embarrassed by. We plan to throw every resource at it to recover it," he said.
"We are giving cast iron guarantees that we will be replacing any stock that is lost."
The DoE said a "definite line of inquiry" was being followed. It said evidence was being collected from premises with a view to prosecution.
A joint investigation is being carried out by the Northern Ireland Environment Agency, part of the DoE, and the Inland Waterways and Fisheries branch of the Department for Culture, Arts and Leisure.
In a statement, the DoE said an anonymous call had been made to the water pollution hotline on Thursday, indicating that a large number of dead fish had been found in the river.
An inspection was subsequently carried out by the Northern Ireland Environment Agency.
The Enler River is a tributary of Strangford Lough.
Councillor Robert Gibson said the local council had been aware of pollution on the river, and a smell in the town, for some time.
"So many years work have gone into this and now it's all gone," he said.
"Today we have lost thousands (of fish). We've probably lost them all, up to a five-metre span of the river."
Eddie Donnelly from the Enler Angling Club said it was the worst fish kill he had ever seen.
"I was devastated by the amount of dead fish. The whole life has been taken out of the river," he said.
A campaign has begun to fight a proposal to remove land from the green belt in Surrey to build housing.
[NEXT_CONCEPT]
A farmer has said he is deeply sorry that his business was responsible for a major fish kill in a County Down river.