A Moroccan court on Monday resumed the trial of 25 Sahrawis accused of killing 13 people, mostly Moroccan security forces, in the contested Western Sahara's Gdeim Izik camp in 2010.
The killings allegedly took place during riots that broke out as security forces cleared the camp near the city of Laayoune in November 2010.
The Court of Appeal in Sale, near the capital Rabat, was packed with lawyers, relatives of victims and defendants, observers, journalists and security forces for the hearing.
The courtroom was dominated by a giant screen broadcasting the hearing. Knives, axes, road signs and hard disks were presented as evidence.
Outside, supporters of the two camps, separated by a line of policemen, exchanged slogans and insults.
"No to impunity for killers!" shouted dozens of victims' relatives, waving Moroccan flags and pictures of soldiers who had died.
"Freedom for political prisoners!" a crowd of Sahrawi activists chanted.
A military court in 2013 sentenced the 25 defendants to jail terms ranging from 20 years to life imprisonment following a high-profile legal drama.
International NGOs condemned the trial as "unfair", and in July the Court of Cassation ordered a new trial in a civilian court.
The Polisario on Monday called on the United Nations to intervene "urgently for the immediate and unconditional release of these detainees".
In a letter to UN chief Antonio Guterres, the group's head Brahim Ghali condemned a "new series of violations" and the "unfair trial of innocent Sahrawi political prisoners and victims of the illegitimate Moroccan military court".
Defence lawyers said they had little faith that the new trial would deliver justice.
The trial "is taking place in very unfair conditions, but we remain at the defendants' side," the defence team said.
Ahmed Atertour, president of an association for families and friends of the victims, said he had "confidence in Moroccan justice to commemorate the memory of our (...) martyrs".
Morocco says Western Sahara, a former Spanish colony under its control, is an integral part of the kingdom.
The Algeria-backed Polisario Front demands a referendum on self-determination for the territory.