Proposals to double the size of a young offenders' institute in Kent have sparked anger among local residents.
The prison houses young men who are serving less than four years
They said they only learned of the Rochester Prison scheme last week when they were invited to view plans before being submitted to Medway Council.
The proposals involve increasing the number of inmates from 392 to 700, and building new accommodation blocks on land backing on to existing homes.
The Home Office has refused to comment on the exact plans.
However, it said Rochester was one of about 30 different prisons across the UK that would need to be expanded to deliver 8,000 additional prison spaces.
The prison occupies the site of the original borstal institution and houses convicted young men who are serving less than four years.
Resident Maureen Shuter said: "They have got loads of land in this area and if they really must have a prison, they could put it elsewhere on land which would not encroach on people's housing."
A campaign to halt the expansion is being lead by Vicki Viles.
"I will rally up as many people as I possibly can," she said.
"The government should not be allowed to walk in and tell people this is what you're getting, this is how it's going to be done.
"This is a foregone conclusion that this is going to be carried out and that is wrong."