Poor jail conditions led to the deaths of more than 30 miners arrested on suspicion of illegal gold mining in central Nigeria last month, investigators said Tuesday, describing their treatment as "cruel and inhuman".

Thirty-three boys and young men were found dead after they were thrown inside a crowded cell in Minna, the capital of central Niger state, in September after their arrest by the Nigeria Security and Civil Defence Corps (NSCDC), a paramilitary government agency.

Survivors recounted being crammed in the cell with poor ventilation, screaming for help and banging on the door which yielded no response from guards on duty.

The claims were confirmed by investigators, who said the deaths took place over 11 hours -- between 8:00 pm and 7:00 am (1900 to 0600 GMT) -- despite distress calls from the detainees.

‘Pleaded for water’

"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 there were 74 detainees in a 20-square-metre cell, which had "a solid metal door, inadequate air flow, no running water, poor lighting and no functioning toilet".

Medical and forensic evidence showed the deaths resulted from "environmental asphyxia, acute respiratory failure caused by prolonged confinement in a severely overcrowded and poorly ventilated detention cell aggravated by heat stress and dehydration", Kure said while presenting the report to the government.

‘Institutional lapses’

The investigating panel concluded that "these circumstances amounted to cruel, inhuman and degrading treatment", he said, pointing at "gross leadership failure, abuse of authority", "major institutional lapses and "serious violations" on the part of the NSCDC officers.

It recommended summary dismissal of officers involved and "prosecution for offences including murder, criminal negligence, torture, and inhuman treatment".

The report would be handed to the prosecutors for further action, Interior Minister Tunji-Ojo said, vowing that officers who concealed or tried to destroy the evidence would be "suspended".

The panel also recommended compensation of 30 million naira ($22,360) to each of the bereaved families and 10 million naira ($7,450) to each survivor.

Niger state authorities initially put the death toll at 37, but the investigating committee said it had established 33 deaths, with 14 of the dead being minors.