PRISONERS will be blocked from using mobile phones in their cells by new technology which will go live at Scottish jails in the coming weeks.

Two prisons have been picked to trial devices that cut off mobile signals over a wide area and prevent people from making or receiving calls, sending texts or accessing the internet.

It follows the ­introduction of new legislation by the Scottish Government which gave the green light to prison management to interfere with wireless signals to prevent the use of illegal electronic communications devices by those in custody.

A growing number of prisoners have been caught with mobile phones in their cells, allowing them to stay in touch with ­criminal associates or direct operations from their cells.

Prison chiefs say inmates have used phones for a range of ­criminal purposes, including organising crimes, harassing victims and maintaining links to gangs.

Access to mobile phones has also been associated with drug dealing, violence and bullying, while some inmates have even been uncovered maintaining ­Facebook or Twitter social media sites behind bars.

Last year it was revealed the prison authorities had investigated 236 ­allegations prisoners were running accounts on social networking sites from behind bars since November 2010, leading to 171 separate pages being shut down.

Blackout technology has been installed at two prisons, HMP Shotts in Lanarkshire and ­Glenochil in Clackmannanshire, which have previously been identified as hotspots of mobile phone use.

The devices will send out a pulse which interrupts all mobile phone signals in the prison area, but does not affect landlines.

Because of their small size and light weight, mobile phones are relatively easy to hide inside cells and have been uncovered sewn inside clothing, slipped into shoes and among the pages of hollowed out books.

Electronic equipment such as CD players or radios are also easily adaptable to create a small space inside where a phone can be easily secreted.

Since 2011, almost 2000 illegal handsets have detected in ­Scottish, with 212 mobile phones recovered from HMP Shotts alone.

Possessing a phone in prison is a criminal offence, and there are currently 91 people serving ­custodial sentences for having one in their cell, or for attempting to smuggle a mobile devices to an inmate.

Justice Minister Kenny MacAskill MSP visited HMP Shotts yesterday to view the progress of work to install mobile signal blocking equipment at the prison, which is expected to go live before the end of the financial year.

Mr MacAskill said: "This Government made it a criminal offence for a prisoner to possess a mobile phone and the Scottish Prison Service has already invested considerably in the use of technology and intelligence capability to detect and prevent the use of mobile phones in our prisons.

"This new legislation will allow SPS to further extend their ­technology to disrupt the use of mobile phones by prisoners and is scheduled to be operational in a matter of weeks."

Colin McConnell, chief ­executive of the Scottish Prison Service, added: "Possessing or attempting to introduce a mobile phone into a Scottish prison is against the law.

"We will do everything we can to make the use of such devices impossible, and the introduction of this state-of-the-art technology is one of a range of measures we intend to take to detect, restrict and disrupt the use of mobile phones in our prisons.

"We will report any discoveries to the appropriate authorities."