The President of the Olympic Council of Ireland, Pat Hickey, has been denied bail and is being held at Bangu Prison in Rio de Janeiro.

The prison is said to house some of Brazil's most dangerous inmates.

It is made up of several penal units - nine of which are penitentiaries and one is a penal institute.

Four are classified as safehouses, one is a penal sanatorium and there are two hospitals.

It is believed Mr Hickey is being held in 'Bangu 10.'

The prison itself has a violent history.

It has been the scene of murders and riots - and has seen several of its officials killed.

Riots there in 2004 left over 30 inmates dead, with some beheaded and burned.

In December 2005, a security chief at the 'Bangu 3' prison became the fifth official from the jail to be murdered in five years.

According to The Rio Times, the prison developed "a deadly reputation" for being under the control of the Commanda Vermelha gang at the turn of the millennium.

It said there were images of prisoners openly selling and taking drugs.

A piece on the penitentiary by Bloomberg last December said: "Outside, smells from sewage ditches blend with whiffs of deep-fried tidbits women buy for their incarcerated husbands from a clutch of vendors near the entrance."

While European youth journalism platform Pandeia described it as "one of the most feared penitentiary complexes in the country."

The Colombian Post says that as recent as last year, almost half the prison guards at Bangu were replaced due to the suspicion they were being paid by drug traffickers.

The prison also houses the Talavera Bruce Women's Penitentiary - with inmates from South Africa, Cuba, France, and other countries.

But it too suffers from overcrowding - prison director Marcus Pinheiro says: "We've got 23 babies here, and only space for 12," refering to the prison's day care centre.

In a recent report, Amnesty International warned "severe overcrowding, degrading conditions, torture and violence remained endemic in prisons" in Brazil.

It found that: "Prisoner revolts were reported in a number of states."