The riots are between hundreds of police officers and people who support an indefinite strike against the Tintaya copper mine owned by Swiss-based Xstrata plc.
Last month two people were killed and buildings set alight in Espinar, in the southern highlands, in a protest against Xstrata, an Anglo-Swiss company that owns a copper mine at Tintaya and is building another nearby.
Many people in the Espinar province have being protesting since last week and they are calling for an investigation into alleged environmental damage caused by the Tintaya copper mine and an increase of the company's contribution from three to 30% to the local authorities.