The mouse-turned-drug-mule was spotted running through a corridor with a “bag of drugs” tied to its tail said Gean Carlos Gomes, director of Barra da Grota prison in Araguaina.

An investigation into the mouse revealed 29 packets of marijuana as well as 23 of cocaine in circulation.

Mr Gomes told G1: “They attached a hook to the mouse’s tail and then used it to carry the drugs and other goods from one cell to another.

“When the animal arrived at its destination, the prisoner took the mouse and removed the hook from its tail.”

Officials said the mouse was set free outside the prison.