At least 21 people died on 30 March when a Peruvian bus plunged 1,000m off a cliff, in the Andean country's second serious transport crash this week, authorities said.

The early morning incident occurred as the bus careened off a highway heading towards Puquio, in the southern region of Ayacucho.

Authorities said at least 37 people were injured and transported to local hospitals.

An official with the Expreso Sanchez transport company, Fernando Sanchez, said authorities were still investigating the cause of the crash but he claimed that poor weather was believed to have been a factor.

Heavy rains have caused deadly flooding and mudslides this month in the Andean nation. The crash occurred one week after a multiple-vehicle collision in northern Peru left at least 34 people dead, including several Christian missionaries.

Bus accidents are common in Peru, where vehicle and highway maintenance is poor and drivers often have inadequate training.