A group of evangelical prisoners released after nearly 12 years behind bars held a press conference in Mexico City to protest the lack of justice for their remaining companions still in jail.

"The truth is that it's very sad for us, and for all the companions that are in jail right now," one prisoner said.

Relatives of the remaining indigenous prisoners have set up a protest camp in the capital's main square.

Released prisoners will not be allowed to return to their own land because of threats on their lives.

A total of 83 indigenous Mexicans were jailed in the case known as the Acteal Massacre, but Mexico's Supreme Court has now ruled that there was no adequate proof of their guilt.