SANTIAGO, Chile (AP) _ A farm worker on Saturday found the mutilated bodies of three men who had been kidnapped last week, the government announced, but four abducted teachers were freed.

Chile's independent Human Rights Commission said it suspected agents of the military governmen had kidnapped all seven.

The government statement said the bodies of Manuel Guerrero, secretary of a dissident teachers union; communist sociologist Jose Manuel Parada, and Santiago Nattino, a painter, were found on a farm near the road to the international airport in northwest Santiago.

''All three were horribly slashed on the throat with deep cuts from a knife,'' said Jose Antonio Ruiz, a farm laborer who discovered the bodies while walking on the road with his wife and son. He said one of the men also had deep cuts across the abdomen.

The four teachers freed Saturday, all members of Guerrero's Chilean Educators Association, were taken from the union office Thursday night by 10 armed men. Nattino, who rented an office next door, was abducted with them.

Three gunmen abducted Guerrero and Parada from a Santiago high school Friday morning as Parada, a human rights activists, brought his son to class. A teacaher, Leopoldo Munoz, was shot in the stomach when he tried to stop the abductors.

No group claimed responsibility for the kidnappings, which Interior Minister Ricardo Garcia called ''a mere police case.'' He assigned a special judge to investigate.

The freed teachers told a news conference Saturday they were severely beaten by their captors. Alejandro Traverso said they were asked ''political questions'' about the organization's leadership and their personal activities. The union leadership is dominated by Marxists.

The teachers did not say why their abductors decided to free them and said they had no information about the three men found slain.

Government officials identifid the slain men six hours after their bodies were found. It said in a statement that it ''laments these sad events, condemns most energetically acts of this nature and hopes for their fullest and fastest clarification.''

A statement by the Human Rights Commission claimed the methods used by the abductors were the same as those by government agents who have seized thousands of dissidents since President Augusto Pinochet, the commanding general of the army, overthrew an elected Marxist-led government in a 1973 military coup.

Monsignor Juan Francisco Fresno, the Roman Catholic archbishop of Santiago, urged the government ''to investigate this crime with greater diligence and promptness.''