At least 22 people have died in clashes between Berber and Arab communities in southern Algeria on the edge of the Sahara desert, the national news agency APS reported Wednesday.
It was the bloodiest toll in two years of frequent clashes between the communities, prompting President Abdelaziz Bouteflika to convene an emergency meeting of top leaders including army chief of staff General Ahmed Gaid Salah.
APS said another 19 people wounded in two days of clashes between Chaamba Arabs and Mozabite Berbers in the M'zab valley had died of their injuries, raising the toll since Tuesday to 22.
Dozens of other people were hurt in the violence on Tuesday and Wednesday, the agency said, citing hospital sources and officials.
Homes, shops, public buildings, cars and palm groves were set on fire in the area of Guerrara and the region's main town of Ghardaia, 600 kilometres (370 miles) south of Algiers.
Nineteen of the killings took place in Guerrara.
Interior Minister Nouredine Bedoui travelled to the stricken region, APS reported, while an AFP correspondent said Algiers-Ghardaia flights were cancelled until Sunday.
"The situation is very serious. This is not just clashes any more, it's terrorism," a Mozabite leader told AFP, adding that armed "gangs" had seized control of the town's entrances.
A security source said police reinforcements were sent from Algiers.
The latest round of clashes in M'zab broke out last week, prompting the deployment of anti-riot personnel who have fired tear gas to disperse crowds.
Hundreds of homes and shops, mostly of Mozabites, have been ransacked in and around Ghardaia since centuries-old good ties between the area's Arabs and Berbers broke down in December 2013, mostly over property disputes and after vandals destroyed a historic Berber shrine in December 2013.
Ghardaia is a UNESCO world heritage site renowned for its traditional white-washed houses and bustling market, selling jewellery, carpets and leather.