The number of prisoners disciplined for taking drugs in jail rose to almost 1,200 last year, according to a new report.

Statistics from the Scottish Prison Service (SPS) show 1,164 adults and young offenders were caught during 2016/17, up from 1,133 the previous year.

The Scottish Conservatives said the increase - up from 634 in 2012/13 - represents a "worrying upward trend".

However the SPS said the rise in those caught and disciplined is welcome as it reflects heavy investment in measures to tackle drug use.

Tory justice spokesman Liam Kerr said: "Yet again we see offenders continuing their criminality within prison walls, an environment which is supposed to be completely secure.

"For the second year running, more than three inmates are being caught using drugs every day, and these figures indicate it's getting worse year after year.

"Detecting and recording these incidents isn't enough - it's crucial the SPS cracks down on this problem and stops these substances slipping through the net."

A Scottish Government spokeswoman said: "Enforcement in prisons is a matter for the Scottish Prison Service (SPS) and these figures show their efforts to tackle drug taking within prisons is making a difference.

"In Scotland, drug taking in the general adult population is falling and drug taking levels among young people remain low.

"We have invested over £630 million to tackle problem alcohol and drug use since 2008. The vast majority of that investment has directly supported local prevention, treatment and recovery services."