Twelve Malawian nationals were killed and 49 others were injured when their bus overturned on the N1 highway near Louis Trichardt in Limpopo.
The bus driver allegedly lost control of the vehicle when the brakes failed, SABC news reported on Sunday.
The bus was en route from Malawi. Its destination has not yet been confirmed.
The bus was not roadworthy and its licence had expired, Limpopo traffic department spokesman Sehlapelo Keshetse told the SABC.