At least six inmates have died within one week following a suspected cholera outbreak at the Kurmawa Maximum Prison in Kano State.
Amnesty International raised the alarm in a post on its official Facebook page, calling on authorities to immediately declare an emergency at the correctional facility.
Amnesty said several other inmates were currently receiving treatment, warning that the death toll could be higher as the suspected disease continues to spread among prisoners.
It urged the authorities to immediately transfer critically ill inmates to hospitals for proper medical attention to prevent further deaths.
The organisation warned that failure to urgently intervene could amount to arbitrary deprivation of life, which it described as a serious human rights violation under international law.
Amnesty also expressed concern over the broader conditions in Nigerian correctional facilities, particularly the prolonged detention of inmates awaiting trial.
According to the organisation, detainees without financial means face greater difficulty having their rights protected, with some spending years in custody without being convicted of any crime.
It further said many inmates were being held in overcrowded and unhygienic cells without adequate food and healthcare.
Amnesty called for urgent reforms to improve conditions in Nigerian correctional facilities and ensure compliance with international best practices.
Six inmates die in one week amid suspected cholera outbreak in Kano prison