Prisoners feel as if they have nothing to lose

Many prisons hold two to five times more inmates than they were designed for.

Carandiru, which has been the focus of the hostage stand-off, holds some 8,000 prisoners, despite being built to accommodate only 3,500.

Packed cells

It is Latin America's largest penitentiary and was the scene of a police massacre of 111 prisoners in 1992.

Authorities had hoped to close the concrete maze in the centre of S�o Paulo, but a rise in crimes and convictions prevented them from transfering prisoners to less crowded facilities in rural areas.

Overcrowding in many of the country's prisons has reached inhuman levels, according to Human Rights Watch.

It says that in densely packed cells and dormitories, some prisoners are tied to windows to lessen the demand for floor space.

Others are forced to sleep on top of hole-in-the-floor toilets.

Routine torture

The spread of infectious diseases, such as tuberculosis and HIV/Aids, is rife.

Medical care for detainees, including those with terminal illness or severe disability, is generally inadequate or non-existent, human rights groups say.

Prisoners have complained of being routinely beaten and subjected to methods of torture including the "parrot's perch" (suspension by the legs and arms from a metal bar), near-asphyxiation and electric shocks.

The high levels of overcrowding combined with low levels of staffing mean that the state authorities have lost control of many areas of the prisons.

No-go areas

These are in effect run by a small and violent group of inmates.

Human rights groups have long denounced the power of criminal organisations, which have special privileges in the prisons.

A study of the S�o Paulo region by human rights organisation Amnesty International, revealed fellow prisoners were responsible for more than 80% of deaths of prisoners in custody.

In many large jails the accommodation blocks are no-go areas for prison officers: prisoners with privileges are responsible for locking cells and for notifying prison officers if an inmate is ill and needs attention.

Inmates in the C�u Azul wing of the men's penitentiary in Manaus have complained to Amnesty that the prison administration was using certain inmates to beat and punish others.