Drones have been flown into Scottish prisons 22 times in the past two years, figures obtained under a freedom of information request show.
On five of those occasions, the unmanned aerial vehicles (UAVs) were found to contain drugs and mobile phones upon interception, The Scotsman reports.
The remaining figures, however, are instances in which the drones were seen within the prison perimeter but were not recovered.
UAVs were seen flying over seven jails, Barlinnie, Saughton, Dumfries, Grampian, Polmont, Perth and Inverness.
A package being flown into Saughton in November 2016 contained 133g of heroin as well as 50 diazepam tablets, three phones and three chargers.
Scottish Labour’s justice spokesman Daniel Johnson said: “Clearly any introduction of contraband into the prison system is wrong and must be stopped.
“The SNP government must ensure our prison service is properly funded and its workers are properly supported so that the public can have confidence in the justice system.”
A spokeswoman for the Scottish Prison Service (SPS) said: “The Scottish Prison Service is aware of the potential for drones or quadcopters to be used illegally and various methods are deployed to prevent contraband from entering our establishments.
“Anyone found attempting to smuggle contraband into our prisons will be reported to the police.”
A Scottish government spokesman added: “The Scottish Prison Service is responsible for the safety and security of prisons and, in liaison with partners, ensures that a range of methods are deployed to prevent or capture contraband entering these establishments.
“The SPS reports any persons found attempting to smuggle contraband to the police.”