'To prevent the situation from further spiralling into violence it is essential that human rights defenders, church representatives and independent observers be allowed to accompany any intervention by the authorities into the disrupted prisons.'

Most of the visiting family members taken hostage alongside prison guards in 29 prisons across the state of São Paulo have now been freed. About 12 casualties were reported, at least two of which as a result of police action.

'While the incidents may have been triggered by the transfer of a number of gang leaders, the extent and scope of these uprisings clearly point at much deeper problems within the São Paulo prison system,' Amnesty International stressed.

With a prison population of over 90,000, and including one of the largest prisons in the whole region, the São Paulo prison system has long been in a state of severe crisis. Amnesty International has documented this crisis, detailing the extreme overcrowding, {deaths in custody}, the systematic use of {torture}, and lack of medical and sanitation facilities, further compounded by the use of under-trained and under-paid prison staff, unable to deal with high levels of gang warfare and regular riots.

Amnesty International recognises the efforts of Dr Nagashi Furukawa, recently appointed State Secretary for Penal Administration, to improve São Paulo's penitentiaries with a progressive prisons building programme, backed with attempts to solve the critical overcrowding in the police stations.

However, these efforts clearly lack the necessary state and federal support to tackle such a long-standing and severe problem.

'The Brazilian government must replace its rhetoric with proper political and financial support for reform of the penal and judicial systems if it is to avoid future disasters like the Carandiru prison massacre of 1992,' Amnesty International said.

Background The Carandiru massacre was one of the most horrific incidents ever documented by Amnesty International in Brazil. Military police stormed Latin America's largest prison, the Casa da Detenção (popularly known as Carandiru) in São Paulo state on 2 October 1992 after a riot broke out. When they withdrew after an 11 hour killing spree, 111 inmates were left dead.

Nine years on, not a single policeman has been brought to justice. The Brazilian authorities must confront the issue of {impunity} as a key step to ending the killing and torture of prisoners.