Chris Grayling: 'Prison plans will save money'
Seven prisons are to close and two more will be partially shut in England.
The Ministry of Justice said it would result in the loss of 2,600 places from "old and uneconomic" prisons and is expected to save £63m per year in running costs.
It says it also plans to build a new super prison with 2,000 places.
Shadow justice secretary Sadiq Khan said people would want reassurance that there would be enough prison places in coming years.
Justice Minister Chris Grayling told the BBC's Matthew Amroliwala that the closures would happen in the next few months but there was enough capacity in the system.