By Tom Gibb Brazil correspondent

The authorities in Brazil say 17 inmates have been killed during more than 24 hours of prison disturbances organised by one of the country's most notorious criminal gangs.

There have been uprisings or murders in nine jails in Sao Paulo state, apparently in commemoration of the first anniversary of the biggest ever prison rebellion in Brazil.

Brazil's overcrowded and understaffed jails have long been run more by the inmates than by the authorities

The violence does now appear to have stopped, but it is part of a larger battle for control of the prison system.

Brazil's overcrowded and understaffed jails have long been run more by the inmates than by the authorities. Uprisings are endemic, with the prisoners using them to make demands - which are often granted - about the running of jails.

Last year, inmates belonging to the most powerful prison gang called the First Commando of the Capital (PCC) used mobile phones to co-ordinate the biggest ever rebellion in 27 jails across Sao Paulo state.

They took thousands of hostages.

Losing control

The government says the latest violence is because the PCC is now losing control.

Most of the killings occurred in fights for influence inside jails between the PCC and rival gangs.

The authorities say increased security over the anniversary stopped much worse violence.

The government also says that the PCC is worried about new measures before congress which will give prison governors more control.

These will allow gang leaders to be isolated and transferred without judicial authority.

But the Order of Brazilian Lawyers disagrees, saying the gangs are stronger than ever, and that it is the government which is losing control.

Over the last year, the PCC has shown it has the capacity to act outside the jails as well, carrying out bank robberies and kidnaps, and organising mass escapes.

It has claimed responsibility for a series of grenade attacks over the last week against prison administration offices in Sao Paulo.