Mark Bridger, who abducted and murdered five-year-old April Jones, has been attacked in Wakefield Prison.
Bridger, who is serving a life sentence, was slashed across the face with a makeshift blade by a fellow inmate on Sunday.
A spokesman for West Yorkshire Police said: “We can confirm that at about 3pm on 7 July a 47-year-old inmate at HMP Wakefield was assaulted.
“His was taken to hospital for treatment. His injuries are not life threatening. He will be returned to prison after treatment. Police are investigating the incident.”
Bridger, a former abattoir worker, was given a life sentence in May.
He kidnapped April before sexually abusing her and murdering her in Wales last October.
He has never revealed what he did with the child’s body but police believe he dismembered her before dumping the body parts near his home in Cienws.