No fewer than 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, urging the authorities to immediately declare an emergency at the correctional facility.
According to Amnesty, several other inmates are currently receiving treatment.
It warned that the death toll could be higher as the suspected disease continues to spread among prisoners.
AI 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.
The organisation said 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.
