At least 13 people have been killed in southern Bolivia after a bus rolled over on a mountain road before tumbling over some 100 metres into a ravine, according to authorities.

Another 26 people were injured in Sunday's crash, which happened in Cieneguillas, a town in the Tarija region south of the capital city of La Paz, police said.

Local media said four of the dead were part of a football delegation from Argentina that was in Bolivia to participate in a festival in the Sucre region.

The accident came a day after a highway crash in another part of southern Bolivia in which two buses collided head-on, killing at least 22 people and injuring 37 others.

Deadly bus crashes are common in Bolivia's highlands where narrow highways often wind next to steep precipices and are known to be treacherous.