Tony Smith, who is serving a 10-year sentence at Swaleside Prison on the Isle of Sheppey in Kent, was allegedly pounced on by two inmates who had been wrongly housed in the vulnerable prisoner wing.
Smith was reportedly tied to a chair and beaten with cans of tuna hidden inside a sock and metal poles, leaving him with a fractured eye socket, broken ribs and a broken jaw.
Smith and his partner Jody Simpson were jailed in February for 10 years following the abuse they inflictedon their son who was just weeks old.
He had been swung around by his ankles, causing his tiny bones to break, the baby was just 41 days old when he was taken to hospital and left fighting for his life with several fractures and septicaemia.
The baby has since been adopted by Paula Hudgell, 50, who is campaigning for tougher sentences for child neglect and abuse.