Pieces of concrete fell from the ceiling into a cell, hitting a prisoner in the prison early on Sunday, guards of the Isotita union announced.
Fortunately, the union said, the prisoner was on the bottom bunk so was not seriously hurt.
“If his cellmate, who sleeps on the top bunk, had been in the cell at the time he would have been injured seriously or possibly fatally, as the pieces of concrete that fell from the ceiling were 40cm square,” the guards said.
The man in the affected cell has said he is dizzy and has stomach pains as a result of the incident, Isotita said.
They added that the incident, in Wing 2B, underlines the concerns they have recently raised about conditions in the prison.
“The danger and unsuitability of the buildings is obvious,” they added.
“We are forced to reiterate the need for urgent renovation and construction of new, modern prisons”.
Otherwise, Isotita said, it is concerned that members will be forced to mourn victims.
The existing wings are proving to be inadequate and unsuitable to meet the needs of prisoners and staff, it added.
Last month Justice Minister Anna Procopiou said the cabinet has approved plans for an upgrade to the prisons which will also include the construction of a new wing.
Upgrading existing facilities and adding a new wing to the prison will solve the problem of overcrowding, she said.