At least 40 people have been killed and several others injured in a bus crash on a high mountain pass in Peru's southern Andes, authorities have said.

The bus was carrying mostly farmers and local tradesmen en route to their homes when it plunged into a ravine on Thursday on a remote mountain highway 610km southeast of the capital, Lima.

As many as 60 people were aboard the bus, which was travelling between Arequipa, Peru's second largest city, and the town of Santo Tomas, near Cusco, Juan Suarez, a police captain, told the AFP news agency.

"There are 40 dead at the moment and I don't have the exact number of wounded, there are about 10," Suarez said.

Bus 'destroyed'

Cornelio Coaquira, the mayor of the nearby village of Velille, was among dozens of villagers who tried to rescue survivors after the crash.

"The bus is completely destroyed at the bottom of the ravine, and the worst of it is that we are isolated here like many towns in Peru, without the communication" that could have saved lives, The Associated Press news agency quoted Coaquira as saying.

Officials are still investigating the cause of the accident.

But Edison Olivares, a teacher in Velille, said the stretch of the highway where the accident took place is in bad condition with many potholes, the AP reported.

Road accidents occur frequently on Peru's mountain highways where many roads are in disrepair.