More than 200 hostages have spent a third night in the hands of prisoners who seized control of a jail in Brazil.
Inmates have camped out on roofs from where they are taunting police
Officials have agreed to the inmates' main demand - the return to the jail of a gang leader - but under conditions which they appear unlikely to accept.
Ednildo de Souza was taken to another prison after briefly escaping. He is accused of organising another riot in April in which 14 inmates were killed.
The riot began on Christmas Day when inmates seized visiting relatives.
Hostage takings in Brazilian prisons often involve their relatives.
The relatives sometimes stay willingly because they think their presence will reduce the chances of the police storming the jail, correspondents say.
Some 150 heavily-armed police are surrounding the notoriously violent Urso Branco prison, in the Amazonian state of Rondonia.
More than 1,000 prisoners are believed to be taking part in the uprising.
Some have camped out on the roofs of the jail, from where they are reported to be taunting the heavily-armed police outside.
Local media have been reporting that the leaders of the uprising have boasted via mobile phone that they have killed at least 16 fellow inmates.
Brazilian police initially dismissed the claim as a negotiating tactic.
Prison authorities say that before de Souza can be transferred back to the jail, the hostages must be released and the prison searched for drugs and weapons.
Negotiations are expected to continue on Wednesday.
Supplies of water, electricity and food have been cut in the hope of tiring out the hostage-takers.
Like many Brazilian jails, Urso Branco prison is badly overcrowded. It was designed to hold 350 inmates, but currently contains more than 1,000.