The death toll is three times what was originally reported by the authorities who have warned it could go higher.
On Saturday afternoon, violence broke out between members of rival gangs at Alcacuz prison in Natal city in northern Brazil, starting a riot which lasted until a dawn raid the following day.
Some of the victims are said to have been decapitated.
Brazil prison riot: 'At least 26 dead' in Natal violence - https://t.co/gr8x2SGhqC— Carolyn Bongiorno (@caroaber) 16 gennaio 2017
Relatives of the inmates were forced to wait anxiously outside the prison gates for news.
As with “other prison riots”:across the country earlier this month, the bloodshed was part of an escalating feud between Brazil’s most powerful drug gangs, which ended an uneasy working relationship about six months ago.
The gangs involved are the São Paulo-based gang Primeiro Comando da Capital, or PCC, and the Rio de Janeiro-based Comando Vermelho.
Their split, which is thought to have happened last year, has unleashed a war with state prisons as their epicenter. The Rio gang has teamed up with five fellow groups around Brazil to counter the PCC’s growing might.
Some 140 inmates have died in gang warfare since the start of the year.
Brazil desperately needs a policy overhaul to end inhumane overcrowding. https://t.co/Hrajw0zOnF #PrisonReform #ReformaPrisional pic.twitter.com/TvOM8zutSB— Human Rights Watch (@hrw_brasil) 9 gennaio 2017