Updated

Authorities say an inmate serving a life sentence in a prison in central Greece has fatally stabbed a guard with a makeshift knife, reportedly after being refused a furlough.

Tuesday's attack occurred as inmates were returning to their cells from the exercise yard. The guard, who was in his 40s, suffered multiple stab wounds to the face and neck and died while being transferred to hospital.

Spiros Karakitsos, head of the prison guards union, said on Greek radio that while prison guards were frequently attacked, it was the first time a guard had been killed inside a Greek prison. He accused the state of failing to adequately staff prisons.

Greece has come under severe criticism from rights groups for the conditions in its overcrowded and understaffed prisons.