Police were called to the Yatala Labour Prison at Northfield this afternoon after a report of suspicious behaviour.
About 12.30pm on Saturday 16 March, two men attended the public area of the guardhouse and tried to drop off a package. They were advised this was against security protocols, but the men dumped the bag and took off from the car park in a vehicle at speed.
Police attended and cordoned off the area. The bag and contents were inspected and found to be non-suspicious.
There were no reports of injuries.
Inquiries are continuing.