Suspected paramilitary fighters killed 12 people in two separate attacks, police said Friday, bringing to 53 the number of deaths blamed on the illegal army in the past week.

Armed men wearing uniforms of the United Self-Defense Forces of Colombia, or AUC, on Friday shot and killed five men and two women in the town of Piamonte, 250 miles south of Bogota, in Cauca state, according to the governor's office.

The attackers called each of the victims by name before shooting them, the governor's office said. The right-wing paramilitaries often have killed civilians they suspected of collaborating with leftist rebels.

In the Narino state town of Samaniego, 130 miles southwest of Bogota, five men were taken from their homes early Thursday morning and killed, according to police Lt. Wilfrido Vasquez. He did not have other details.

"Everything indicates that they were paramilitaries because (the victims) were people who helped the guerrillas," Vasquez said.

Authorities have blamed the paramilitaries for the deaths of 41 others in the past week, including a congressman, a union leader, and 24 unarmed peasants in the village of Buga.

In addition to those 53 deaths, the army said it had discovered 14 more bodies in a mass grave, apparently victims of an earlier massacre by paramilitaries. Army officials did not provide more details on the mass grave in Albania, a town in southern Caqueta state.

Human rights official Eduardo Cifuentes called Thursday for an investigation into whether the army unit nearest Buga could have acted to prevent the massacre.

The unit operating in Valle de Cauca state belongs to one of three brigades highlighted in a report issued last week by the U.S.-based Human Rights Watch alleging the Colombian army regularly collaborates with AUC.

The Colombian military receives millions of dollars in U.S. aid to fight illegal drug production.

Colombia's 37-year civil war pits leftist guerrillas against government forces and the AUC.

President Andres Pastrana's government began a new round of talks with the guerrillas Friday. He has refused to negotiate with the AUC.

The AUC and two rebel groups are on Washington's list of international terrorist organizations.