New homes could be built on green belt land in Gloucs because of government intervention, the county council says.
As part of its structure plan, which outlines where future buildings may be located, the council did not want any green belt development before 2016.
But regional planning body Government Office for the South West (GOSW) has intervened, says the council.
Now it faces abandoning its structure plan or opening up the possibility of development on green belt land.
In February, the council said in a draft structure plan that Gloucester and Cheltenham would bear the region's house-building burden with 1,375 homes planned over 11 years.
But on 1 April, after a six-week consultation period, the government said it would permit green belt development before this time.
In a letter to Gloucestershire County Councillor Peter Bungard, the Government Office for the South West (GOSW) said: "After careful consideration the Secretary of State is of the view that the distribution of housing distribution proposed by the structure plan is unsatisfactory."
Mr Bungard said: "If the county council accepts this direction, it would result in an additional 2,500 houses being located at Cheltenham principal urban areas - most likely in the green belt."
Mr Bungard added: "Despite the council working closely with the GOSW to prevent such intervention happening, the secretary of state is still not satisfied.
"This is a very disappointing outcome as far as the council is concerned, as it was hoped that an up-to-date structure plan could be adopted in the near future."
A decision on the structure plan's future will be made after the county council elections on 5 May.