A traffic accident involving a truck and two buses left at least 20 people dead and 40 people injured on the road linking the southern cities of Arequipa and Juliaca, a police spokesman said.

The huge early morning pile-up was the region's second large-scale crash in 24 hours, after 12 people were killed and 39 injured on Monday when a bus overturned in the southern Andean state of Ayacucho.