More than 15kg of drugs and 16,000 pills have been seized at Scottish jails in the last five years.

The haul includes nearly 12kg of cannabis, 3kg of heroin and about 1kg of cocaine and amphetamines.

The largest quantity of drugs were recovered from prisoners at HMP Shotts, Scottish Prison Service (SPS) figures show.

It was followed by HMP Grampian, even though the Peterhead prison only opened in March 2014.

An SPS spokeswoman said the service was investing in new technology to crack down on drug use.

"A comprehensive range of robust security measures are in place to prevent the introduction of contraband into our prisons," she said.

"Significant investment continues to be made in the development of new technology and staff training to detect, deter and reduce the availability and supply of illegal drugs.

"Anyone found in possession of contraband is reported to the appropriate authorities."

The figures do not include a specific category for new psychoactive substances, better known as legal highs.

Jails watchdog HM Inspectorate of Prisons for Scotland recently warned a rising number of prisoners are abusing legal highs.

The figures appear to show a dramatic drop in the amount of drugs seized in prisons last year, from 4.9kg in the 2015/16 financial year to less than 1kg in 2016/17. However, four prisons were not included in the most recent annual figures.