Among the victims of the attack on two bars late Sunday were "four minors", the joint command said in a statement.

The villagers were mowed down at San Miguel del Ene in a coca-growing valley where members of the Maoist Shining Path group operate.

The killings risk inflaming tensions amid a polarized campaign for the presidency between leftist Pedro Castillo and his rival from the right, Keiko Fujimori.

The authorities blame the attack, which police said Monday had claimed 18 lives, on fighters led by guerrilla leader Victor Quispe Palomino, or Comrade Jose.

Pamphlets were found at the scene of the killings warning people not to take part in June presidential elections, according to officials.

Alerted to the crime by neighbors in the early hours of Monday, police found the bodies -- some of them burnt -- in two bars on the banks of a small river.

President Francisco Sagasti ordered police and soldiers to the area, and a specialized terrorism unit has been tasked with investigating the killings.

Most of the Shining Path's top leaders have been detained by the authorities, but Comrade Jose and other militants remain at large and active in Peru's coca-growing region, where the government says they collaborate with drug traffickers.

Comrade Jose's brother, Jorge Quispe Palomino or Comrade Raul, died in January due to injuries sustained in an attack on a "terrorist camp," according to the authorities.

With Colombia and Bolivia, Peru is one of the world's main producers of coca leaves from which cocaine is derived, according to the UN.

Castillo and Fujimori have condemned the attacks that for many are reminiscent of Peru's violent armed conflict from 1980 to 2000.