Outbreaks of violence between rival Arab and Berber factions have broken out in several desert towns in Algeria, resulting in the death of at least 18 people.
Clashes erupted at the weekend in the M'Zab valley, a desert area some 600 km south of Algiers, famous for its Unesco protected fortified citadels.
Hostilities between the two ethnic groups were reported in the towns of Ghardaia, Guerrara and Berriane, with rioters throwing rocks and setting fire to businesses and houses.
Fighting intensified at the beginning of this week, when local media reported firearms were also used and three men killed.
At least another 30 people were injured and extra security forces have been deployed in the region to quell the violence. Interior minister Noureddine Bedoui has gone to Ghardaia.
La Soir D'Algerie newspaper reported a policeman was hit by car was among the victims.
Cohabitation between the Arab and Mozabite Berber communities has often been problematic, with disputes on land or business sporadically erupting into violence.
Local rights groups condemned the unrest as "unacceptable" and accused the government of repeatedly failing to properly address the recurring issue.
"The state's failure in this matter is obvious and shows how the "total security [policy]" has never built a lasting solution to this conflict," The Algerian League for the defence of Human Rights said.