Serious organised crime groups took out contracts worth £2.8m for attacks on rivals in Scotland’s jails last year.

The Scottish Prison Service, which released the figures, is dealing with the consequences of a huge increase in convictions for gang-related crimes.

It said the number of prisoners linked to serious and organised crime groups (SOCGs) had doubled in six years.

Prison staff had their cars firebombed and six officers were charged with criminal offences last year after being influenced by criminals.

The Prison Officers Association in Scotland said the constant threat caused by the presence of so many gang members had left its members under massive pressure.

Scottish Prison Service (SPS) intelligence reports identified 538 individuals linked to serious and organised crime, roughly 8% of Scotland’s total prison population.

Of those, 176 have been linked to 54 different SOCGs, many of whom operate throughout the UK and some globally.

The figure includes 23 “principals” who either lead SOCGs or operate at the highest level.

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