Health Minister Roselyne Bachelot said the cancer overdose radiation scandal is much higher than previously thought following the discovery of 300 new cases.
A total of 721 men suffering from prostate cancer are now known to have received excessive amounts of radiation due to a calibration error at the Epinal general hospital between 1999 and 2006. Twenty-four were seriously affected and five of these have died.
When the scandal was first revealed earlier this year, only 421 cases were identified.
Health authorities are trying to contact the estimated 4,500 patients who were treated at the centre.