New whistling codes are being used in the prison yards to let smugglers know it is safe to throw drugs over the wall.
The new method has become very popular among the prisoners and a number of different whistles are being used.
The prisoners use these different whistles when they’re ready to receive the drugs at Cloverhill prison.
The shipments are being organised by a senior drugs boss.
Just last weekend a man who was convicted of murder took a prisoner hostage and threatened his life. There was a two hour stand off when the prisoner finally let his hostage go.