Prisons are failing to carry out prompt and thorough investigations into alleged discrimination behind bars, a watchdog has warned.
A report detailed how inmates were left without a response to complaints for several months, while training of staff to deal with equalities issues is "inadequate".
The Prisons and Probation Ombudsman (PPO), which analysed more than 200 cases lodged over five-and-a-half years, flagged up a failure to engage with and directly address issues of discrimination.
It said: "In some cases, managers respond to complaints about discrimination by simply asserting there has been no discrimination, without any attempt to investigate or to address the complaint."
In one instance highlighted in the PPO's assessment, a "profoundly deaf" inmate was left without one of his hearing aids for more than a year after it went missing when he was transferred from one establishment to another.
He said he felt discriminated against, arguing his disability had not been taken into account, and his complaint was upheld by the Ombudsman.
In another case, a prisoner submitted a complaint about "harsh treatment" on the induction regime where he was held but five months later he had still not received a response. When questioned, the jail admitted it had "mislaid" the complaint.
Elizabeth Moody, the acting Ombudsman, said HM Prison and Probation Service has a duty to ensure equality and prevent discrimination.
She said prisons need to allocate sufficient resources and properly trained staff to investigating discrimination complaints, while ensuring allegations are not ignored or "glossed over".
Ms Moody added: "We recognise that this is not always easy to do this when resources are tight. Unless these steps are taken, however, prisons - and the wider public - cannot be sure that they are treating prisoners fairly and equally."
The report looked at a sample of 208 complaints involving discrimination issues which were submitted to the PPO from January 2012 to July 2017 and subsequently investigated.
Of the personal characteristics protected by the Equality Act, the most common complaints investigated by the PPO alleged discrimination on the basis of religion, followed by disability, race, gender, nationality, sexuality, and then age.