An attempted escape by inmates from Domokos high-security prison, near Lamia in central Greece, was thwarted on Tuesday after wardens discovered a ditch measuring 10 meters deep and 50 cm wide, authorities said.
According to the Justice Ministry, which has ordered an investigation, no one had escaped when prison officials found the ditch under the floor of a prison cell shower.
It was the third attempted breakout from a Greek prison since last year.
In December 2015, an escape plan was foiled at Trikala prison in northern Greece, again after wardens found a tunnel dug by two inmates.
Three months earlier, in August, long-term convicts were caught in the act of digging their way out under a prison on the island of Corfu when a passing dog, on the street above, heard them and started barking. The tunnel was at least 15-meters long and authorities said around 11 prisoners were planning to escape through it.