Huntley was convicted of the murder in December 2003
Child killer Ian Huntley has been attacked with boiling water by another inmate at the high security Wakefield Prison, in West Yorkshire.
Grimsby-born Huntley was attacked on Wednesday on the health care wing of the jail, which houses some of the most dangerous prisoners in the country.
Prison sources confirmed Huntley had been the victim of the attack and he was being treated at the site.
Huntley murdered Jessica Chapman and Holly Wells in Soham in August 2002.
A spokeswoman for the Prison Service said: "We can confirm a prisoner on the health care wing at HMP Wakefield was, on 14 September, attacked with boiling water by another prisoner.
"He is being treated by health care staff at the prison and an internal investigation has been launched.
"While staff monitor prisoners carefully, high security prisoners are, by nature, a particularly challenging group to manage and while staff are always vigilant, it's impossible to prevent incidents of this nature occasionally happening."
Schoolgirls Holly and Jessica were both aged 10 when they were murdered in Soham, Cambridgeshire.
Ian Huntley was convicted of their murders at the Old Bailey in December 2003.