Kent prisoners could be released early from jail – starting as soon as next week.

Up to 550 non-violent and non-sexual offenders in the UK who are serving four years or more but less than life will be automatically freed halfway through their sentences.

The Ministry of Justice will be introducing the scheme on June 9, to tackle the issue of overcrowded jails, which now house a record 83,000 in England and Wales.

The eight prisons which could be affected in Kent include Blantyre House in Goudhurst near Tunbridge Wells and East Sutton Park in Maidstone.

The Prison Service warned that jails which failed to let out offenders from June 9 would amount to ‘unlawful detention’.

A Ministry of Justice spokesman said: “In order to enhance public protection we are at the same time extending probation supervision to the end of the offender's sentence instead of the three quarters point.

“This means that for the whole of the second half of the sentence they will be subject to licence conditions and liable to immediate recall to prison at any time if their behaviour gives cause for concern.”

Shadow justice secretary Nick Herbert described such early release schemes as ‘underhand’ although this latest plan was not opposed by Parliament.

Mr Herbert said: “Releasing prisoners early when they have only served half of their sentence undermines trust in the criminal justice system.”

The change will not apply to prisoners serving sexual and violent offences.