The French Ministry of Justice is planning to install landline telephones inside of all 50,000 of its prison cells, following a successful trial at one jail in Montmédy in the north-east of the country.

The move comes in a bid to reduce the illegal trade in mobile phones inside of France’s 178 prisons, which the authorities have struggled to control.

Inmates will be allowed to call pre-approved numbers on the landlines, once the contract, currently out to tender, is awarded.

'Pre-approved numbers'

The new arrangement will supersede the use of public call boxes, the use of which requires prison officer supervision.

Access to public phone boxes has also been a cause of tension during limited recreation periods, according to prison authorities.

The Ministry of Justice believes that the move towards in-cell communication will aid family reintegration and societal rehabilitation.

However, prisoner advocacy groups have criticised the planned call charges of 80c per minute.

The successful operator must finance the installation and operational costs of the service through the call charges, the Justice Ministry has said.