Ministry of Justice (MoJ) staff have been banned from calling prisoners “residents” or describing cells as “rooms” after it faced questions over whether it had opened a “soft-touch” jail.

A style guide has been issued to all MoJ, prison and probation employees, as well as private jail contractors, to make clear what terms can and cannot be used.

Staff have been told not to refer to “service-users” or “clients”, instead being urged to call them prisoners or offenders.

It comes after the Justice Secretary defended a new “smart” prison designed to drive down crime.

During a visit to HMP Five Wells in Wellingborough, Northamptonshire, in March, Dominic Raab said inmates at the category C prison needed to be given “a sense of what life on the outside looks like” because “we are not going to lock everyone up for life”.

The 1,700-capacity prison does not have bars on its windows, and will provide prisoners with access to a gym, snooker table, table tennis table and a tablet to gain new qualifications.

At the time, prison staff said they would describe cells as “rooms” and prisoners as “residents” to aid their rehabilitation.

During the visit, Mr Raab said: “I’m interested in punishment, because that’s what the public expect, but I’m not really interested in stigmatising in a way that’s counter-productive to my aim of driving down re-offending.”

Asked if HMP Five Wells was a “soft-touch” prison, Mr Raab said there was “no doubt about it, prisons need to be secure, they need to punish, but they also need to try to give, because most offenders are going to be released, a sense of what life on the outside looks like”.

But the MoJ has now said staff must stick to the approved language and change any literature or products that fail to adhere to the style guide. The rules will only apply to adult prisons as youth custody facilities are exempt.

Media reports suggested the guidance was issued amid fears that use of the phrases was damaging public confidence in the criminal justice system, but this has not been confirmed by officials.

A Prison Service spokesman said: “Our style guide will ensure clear and consistent language is used in all communications relating to adult prisons and probation services.”