At least 37 people were killed and dozens injured after a bus plunged into a ravine in the Arequipa region of southern Peru, local authorities said on Wednesday.

The fatalities included 36 people who died on site, and another person who died in hospital, said Walther Oporto, Arequipa's regional health chief, citing firefighters at the scene of the accident.

The bus struck a van and veered off the road into a ravine, Oporto said in a television interview.

The Arequipa government said on social media that 26 people were being treated for injuries, three of them in serious condition. It added that an unofficial report from the highway patrol confirmed 16 deaths.

The early-morning accident took place on the Panamericana Sur highway in Arequipa's Ocona district.