The mourning period, held in the southeastern region of Puno, came as Prime Minister Alberto Otarola is set to appear in the opposition-dominated Congress, seeking a vote of confidence in his cabinet - a constitutional requirement to lead a new government.

Otarola regretted the deaths on Monday night and said the unrest was caused by organized attackers financed by "dark" money, in a day in which at least 68 civilians and 75 police officers were injured according to the local ombudsman.

Social protests have left a total of 39 dead so far in different parts of the country.

Authorities called on prosecutors on Monday to launch investigations against those responsible.

Demonstrators are continuing to demand President Dina Boluarte's resignation, the closure of Congress, constitutional changes and Castillo's release.

Castillo is serving 18 months of pre-trial detention while being investigated for "rebellion" after trying to close Congress, a charge he denies.

Images from local media showed looting of businesses in Puno on Monday night and the region's Juliaca airport remained closed on Tuesday.

Likewise, airport operations in the Andean region of Ayacucho remained suspended as a security measure.

The Inter-American Commission on Human Rights has announced it will visit Peru this week from Wednesday to Friday to assess the situation.

(Reporting by Marco Aquino; Editing by Alistair Bell)