The self-inflicted injuries were discovered by a prison guard at 7am and although they were reportedly not serious, he was taken to the sick wing of the prison.
However, it is not known how he obtained the razor, as he is banned from having them, despite some of the initial restrictions of his suicide prevention regime being lifted recently.
Breton reported Ruth, 6, and Jose, 2, missing from the Cruz de Conde Park in Cordoba on October 8, 2011.
Less than 24 hours earlier, he had picked them up from school in Huelva, where they live with their mother since the couple had separated just weeks earlier.
However, he was remanded to prison on October 21 for his alleged involvement in their disappearance. He is charged with illegal detention and faking a crime.
Several days before the disappearance he had reportedly said “something big is going to happen here”.
Police have searched for clues to the whereabouts of the two children, mainly at properties belonging to their parental grandparents, and have been convinced from the outset that Breton is lying, but have no evidence against him.