PRISON bosses have shut down more than 170 Facebook accounts being run by inmates on mobile phones smuggled into Scotland's jails.
Bosses probed 236 allegations prisoners were running accounts on the social networking site from behind bars since November 2010.
As a result, 171 pages were shut down over fears they were being used to taunt victims and communicate with fellow criminals.
The sites are mainly run from inside jails using smartphones.
The problem became so endemic the Scottish Prison Service had to instigate a Facebook Policy in November 2010.
New laws introduced in 2010 mean anyone caught with a mobile phone can have up to two years added to their sentence.
Since then the number of investigations has soared – from 13 in the last two months of 2010, to 91 in 2011 and 132 last year.
Prison bosses were able to shut down seven sites in 2010, 70 in 2011 and 94 in 2012.
The figures, released under freedom of information legislation, reveal more than one in five accounts closed down last year was being run in private prison HMP Addiewell.
The West Lothian jail holds less than one in 10 of Scotland's prison population, but last year 22 of the 94 accounts shut down originated there.
Prisoners at Addiewell stay in en suite cells and have access to individual flat screen televisions.
Maximum security HMP Shotts, which houses hundreds of violent criminals, including those serving life for murder, had 26 pages investigated last year, with 20 shut down.
Only HMP Barlinnie and HMP Greenock had no Facebook sites shut down last year.
Last year, it emerged killers Derek Morgan and Lloyd Patterson – who are serving life terms at Bowhouse Prison, Kilmarnock, for the murder of Craig Archer in Glenrothes in 2006 – were posting while behind bars.
The pair posted pictures of themselves, while Patterson posted taunting updates.
David Gilday, who was jailed for eight years for a hammer attack in Kirkcaldy committed after being freed half-way through another 10-year term, posted: "Got such an easy life."
Scottish Conservative chief whip John Lamont said: "This is another instance in which the victims of crime have been let down."
And Scottish Labour's Lewis Macdonald MSP said: "It is unacceptable inmates have unauthorised access to the internet. It is even worse they use it to brag about their time behind bars.
"The prison service must do more to clamp down on phones in prisons and this shows how much work is needed to be done in getting basic security right."
A Scottish Prison Service spokesman said: "The Scottish Government changed the law in 2010 to make the possession in prison of a mobile phone a criminal offence.
"SPS staff are vigilant in their detection of mobile phones through improved intelligence, increased use of search dogs, and the use of technical equipment.
"Where there has been unlawful activity, steps are taken to remove the sites."