A 14-month probe into the activities of a prison guard suspected of smuggling drugs into a jail in Trikala, central Greece, has revealed that drug-dealing rackets are rife in correctional facilities across Greece.

The police operation, which began in May 2011, has uncovered evidence suggesting that the 43-year-old Trikala Prison guard supplied a specific inmate with narcotics, which he in turn distributed through another 30 inmates. That same inmate allegedly set up a similar racket in Alikarnassos on Crete after being transferred to the prison there, while the Trikala guard continued his business as usual, working with a different inmate.

By following the thread of the activities of the 43-year-old -- who was arrested on Sunday along with another 28 suspects -- investigators uncovered rackets in the jails of Patra, Domokos, Chios and Avlona, where inmates ran dealing networks both inside and outside the prisons, using mobile phones and the Internet to coordinate their activities.