Prison bosses in Liverpool are taking action to stop inmates from using a catapult to smuggle in drugs.
String was fired over the fence with the catapults
Prisoners at HMP Liverpool were using parts of rubber gloves tied to cell bars to fire out a weight, with long string attached, over the fence.
Accomplices would then attach drugs or mobile phones which were reeled back in through the cell windows.
The Prison Service would not confirm reports that grilles were being put on all cell windows to stop the practice.
But a spokesman confirmed that measures were under way to prevent the scam happening again.
He said: "Prisoners at HMP Liverpool were attempting to bring drugs into the prison in this way.
"This was detected by staff, the items were recovered and steps are being taken to prevent prisoners from attempting this again.
"HMP Liverpool has been working very closely with the local police to prevent drugs entering the prison and anyone attempting to do this will face criminal charges."