An Asian inmate was badly beaten in a racist attack weeks before Zahid Mubarek's murder at the same young offenders' institution, it has emerged.
Robert Stewart is serving a life sentence for killing Zahid
The teenager was left without help for 24 hours and, when he did receive treatment, needed 19 days in hospital with a broken jaw and other injuries.
The inquiry into Mr Mubarek's death was told the Prison Service's Muslim adviser was "deeply shocked".
He wrote to the governor of Feltham Young Offenders' Institution.
The inquiry was told the letter from Maqsood Ahmed to Nick Pascoe said he was "deeply shocked" staff appeared "so casual" about the attack by two white inmates.
Mr Ahmed claimed the two alleged attackers were "allowed to carry on with their practice of harassment and beating of young vulnerable Muslim prisoners."
Although the two assailants were immediately identified to staff, they were never disciplined.
Despite the victim and his Asian friend, who was also attacked, giving statements at the time, police were not called in for a year.
When they investigated they charged the suspects with causing actual bodily harm.
The letter detailing the assault claims emerged on the final day of hearings into the killing of Zahid, 19, by his racist cellmate.
Zahid died days after the assault from massive injuries
Robert Stewart, 24, of Hyde, Greater Manchester, battered Zahid with a table leg in March 2000. Zahid, from Walthamstow, east London, died seven days later in hospital.
The unnamed victim of the first assault was watching television with his friend in January 2000 when two prisoners allegedly subjected them to racist insults and then attacked them.
Mr Ahmed said it was a "very serious incident which could have resulted in death.
"I am deeply shocked to learn that staff at Feltham seem to be very casual about this racist incident and have resumed 'business as usual' so soon after the tragic death of Zahid Mubarek," he wrote in 2001.
He added: "We do not appear to have learnt anything from past experiences and Muslim prisoners rightly feel discriminated against, unsafe, and completely let down by HM Prison Service."
He said it was of "great concern" that Muslims felt they were not treated equally by the complaints system and believed they would be further victimised if they complained.
The inquiry's initial phase ended on Friday and the chairman, Mr Justice Keith, is expected to report later this year.