Three were killed a day earlier in clashes between Arabs and Berbers.
The sometimes deadly confrontations erupted with regularity in the region last year. Thousands of security forces ensured calm, but the clashes spiked again at the beginning of July.
The APS news agency said 14 people died of injuries from "projectiles" in Guerrara, 120 kilometers northeast of Ghardaia, where a 15th person was fatally injured when hit by a rock to the head.
Three people had been killed in confrontations a day earlier, bringing the total 48-hour death toll to 18. Dozens of others were injured, including seven in serious condition, APS said.
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There was no immediate reaction to the latest violence from Algerian authorities.
Riot police moved in to quell the clashes that included fires and vandalism targeting shops, cars and public buildings in the towns of Guerrara, Ghardaia and Berianne, 40 kilometres north of Ghardaia, the news agency reported.
Ghardaia, a UNESCO world heritage site, has been at the epicenter of the unrest. Members of the local Berber community, known as Mozabites, speak their own language and follow a different school of Islam than the majority of Algerians.
The two groups compete over limited jobs, land and housing in the impoverished south.