It is believed they were on their way to buy sweets when Huntley, then aged 28 and working as a school caretaker, lured them back to his home and killed them.
Their disappearance made national headlines and led to police appeals.
The girls bodies were found in a ditch a fortnight after they went missing.
Huntley was arrested on the same day.
His girlfriend Maxine Carr was also jailed in 2003 after being found guilty of conspiring to pervert the course of justice for giving him a false alibi. She has since been released and given a new identity.
The Ministry of Justice has previously said Huntley’s crime “remains one of the most shocking and devastating cases in our nation’s history, and our thoughts are with their families”.
The attack in February was not the first time Huntley had been attacked in prison, after a previous incident in 2010 resulted in him needed 21 stitches.