The investigating committee found that the raid on the miners had been conducted without an approved operational order, proper planning or consultation with the Mining Marshals Unit.
It said that 50 detainees had been held in a cell measuring about 20 sq m, with no running water or functioning toilet, and inadequate food, drinking water and airflow.
Adults and minors were detained together, and some detainees were held beyond lawful detention periods.
Officers reportedly ignored repeated calls for help, despite a medical worker having raised concerns about the conditions.
“Detainees repeatedly banged on cell doors and walls, shouted for assistance and pleaded for water,” said the head of the investigating team, Jonathan Kure.
“These distress calls were heard by officers assigned to nearby duties… but were not acted upon.”
Kure said the detention conditions amounted to cruel, inhuman and degrading treatment.
“The tragedy demonstrates the consequences of systemic disregard for detention standards, supervisory responsibilities and the welfare of persons in custody,” he added.
The investigating committee also recommended compensation of 30m naira (£16,683; $22,285) for each of the bereaved families and 10m naira for each survivor.
