Nine inmates have died in a riot at a maximum security prison in Brazil.

The 30-hour riot ended on Monday after prisoners released the last of 23 hostages they took after demanding to be transferred to another prison.

Some 220 prisoners, armed with guns and knives, freed their remaining four captives from inside the walls of Taubate maximum security jail, 135km (85 miles) north of Sao Paulo, late on Monday.

Earlier they had freed 19 other hostages, including four children who had been visiting relatives at the jail.

According to local police none of the hostages were harmed but three of the dead were found decapitated and other bodies were mutilated.

Power cut off

In a bid to end the siege police had cut off the prison's electricity.

The inmates were demanding transfers to other, less severe prisons, as well as an end to overcrowding.

Tensions in Brazilian prisons - notorious for poor conditions - usually rise before Christmas and New Year, when inmates want to be with their families.

But police say that the jail is not overcrowded, and that inmates wanted transfers only because they hoped that less rigid security at other jails would make escape easier.

Initial reports said that among the dead was an alleged serial killer known as the Park Maniac, who was serving 121 years for raping and robbing nine women in a Sao Paulo park.

Francisco Assis Pereira was also facing trial on charges of killing 11 women.

Taubate prison holds Sao Paulo state's most dangerous prisoners.

Three prisoners were killed and six injured in the last riot there in November.