Police Scotland, in partnership with the Scottish Prison Service, have been working at HMP Perth to tackle drugs entering the prison.
Between Wednesday, 22 June and Friday, 24 June, local officers carried out both covert and overt patrols around the perimeter of HMP Perth and the surrounding areas.
Specialist resources, including mounted branch and high-visibility patrols, were deployed during the final day of the operation (Friday, 24 June) to deter any offending, police said.
During the covert activity, police officers stopped and searched four men – including one man who was flying a drone near the prison.
Police Constable Scott Birrell, Prison Liaison Officer, said: “Tackling drug misuse within prisons is a priority for Police Scotland and this significant operation reinforces our determination to target criminals.
“Drug misuse brings nothing but misery and people’s lives can be ruined.
“We will continue to use every tool and tactic at our disposal to remove these illegal substances from our prisons.
“We depend on the continued support from our partners and our local communities and I would urge anyone who has any information, or concerns surrounding drugs, to contact police.
“Anyone with concerns can call officers on 101 or alternatively, call Crimestoppers anonymously on 0800 555 111.”
A Scottish Prison Service spokesperson said: “The SPS is committed to tackling the harms caused by misuse of contraband substances in our prisons.
“We have invested in technology to better detect suspicious substances, working closely with partner agencies to gather relevant intelligence.
“Rapiscan machines which specifically detect substances that may be concealed in items of mail and personal property, are now in use in all of Scotland’s prison.
“Individuals will use various methods, including drones, in an attempt to introduce contraband to our prisons.
“We deploy a range of robust security measures to prevent this and work closely with Police Scotland to investigate and identify any perpetrators.”