The accident in Ghardaia, 600 kilometres (370 miles) south of Algiers, claimed two more lives -- the bus driver and a companion -- and injured 16 others.
Last week, Algeria began repatriating thousands of illegal workers to Niger in an operation likely to last several months.
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Niger Prime Minister Brigi Rafini urged Algiers last month to return people from his country "who number 3,000, are jobless, and unfortunately live by begging".
Algeria has become the North African destination of choice for sub-Saharans seeking a better life.
Niger, one of the world's poorest nations, has the planet's highest birthrate averaging 7.6 children per woman. Emigration is massive.
In October last year, 92 Nigerien migrants -- again mostly women and children -- died of thirst while crossing the desert to try to reach Algeria.