An independent monitoring board has criticised the justice secretary's decision to close Blundeston Prison.
The board, which publishes an annual report on the Lowestoft jail, has called the plans "ill-conceived, premature and rushed".
In an open letter, seen by ITV News Anglia, it said HMP Blundeston had consistently been praised for the excellent relationships between staff and prisoners.
The prison is due to close by the end of the year as part of a government plan to bring in new "super prisons".
But the IMB questioned whether those relationships would be as strong:
"Prisoners who appreciate the support they get at the prison are unhappy at the closure which de-stabilises their rehabilitation, moves them to another prison and means, in some ways, they will have to start all over again."