The Minister of Interior Ogbeni Rauf Aregbesola on Monday confirmed the deaths of five inmates and seven injured inmates at the Ikoyi Centre of the Nigerian Correctional Service.
The inmates were electrocuted in their cells following a power surge at about 7am.
Aregbesola, who visited the facility for an on the spot assessment, declined to name the victims', saying that their families are yet to be notified.
The minister said he would probe the incident and that a coroner's inquest report would confirm the exact cause of death.
He commiserated with the families and pledged to work towards averting a similar incident.
Aregbesola said: "The government of the federation deeply regrets the unfortunate incident. It happened this morning at about 7am.
"I have gone round to see the cell where this incident occurred and I want to express to Nigerians the deep sympathy of the Federal Government and all of us about the circumstances of the accident that led to some loss of lives in one of the cells.
"I'm going to put together a team that will go into the root of how the accident occurred with a view to ensuring that no such thing happens again.
"This is quite sad distressing and disturbing we pray for the repose of the soul of the deceased are equally pray that God will give the families that are bereaved the fortitude to bear the loss.
The victims' identities could be publicised after their families were notified, he said.
Aregbesola added: "We have not yet informed the families of the deceased but that will be done, before we make it public.
"The law recommends in this instance a coroner's inquest which will reveal what the exact cause of the deaths were, but beyond that, we will look into everything about it, the circumstances, the how, why, and generally cause of this."
He said President Muhammadu Buhari was" quite disturbed" about the incident and that "it is highly regretted".
Controller-General of Corrections Ja'afaru Ahmed confirmed the incident.
He said the facility was overcrowded but that he could not speculate as to whether overcrowding was a reason for the accident.
Ahmed said: "Our primary responsibility as a service is safe secure humane custody that's why I've been doing over the years but incidents do happen even in our homes. It is here that generates a lot of controversy or interest because it happened in a government facility there's always that perception. But these are incidents that always happen living in the house.
"There was actually an electricity surge, the cause of which we don't know yet because we still have to investigate and investigation will reveal the when how and why it happened. As I speak to you we have five inmates that died and seven are at the hospital I gave you this number because I want to avoid speculation and everybody knows that there is overcrowding in this facility. "
"This facility was established in 1955 for just 800 inmates but it is locking 3113 and out of this number 2680 are waiting trial so it's just barely about 400 plus that are convicted felons which the correctional or custodial centre needs. because we need convicts not awaiting trial persons we have other facilities where we can move these people to if they had been convicted. We can move them to other centres that are less congested just like the soul prison which has about 1," he said
Ahmed said "Like the minister has said there is a concerted Effort on the part of the government and especially this present administration to turn around Fortunes of the Nigerian correctional services now starting with change of name and then the custodial and non-custodial.
"We asked Nigerians to be patient with us this government has a renewed interest from 2016 it has intervened to turn Around The Fortunes of the Nigerian prison service and now named Nigerian correctional service" .
"It's an unfortunate incident we do not want to lose any life we want to return life even for those who are condemned", Ahmed stated.
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