BOGOTA, Colombia (Reuters) -- The bodies of three policemen who had been
                  taken prisoner by Marxist rebels 18 months ago were found with their throats slit
                  and dumped in a mountain region of northeast Colombia, police said on
                  Thursday.

                  The corpses were discovered late on Wednesday near the town of Chita, in
                  Boyaca province, after a clash between the army and Revolutionary Armed
                  Forces of Colombia (FARC) rebels in which two rebels and a soldier died.

                  "We found the three bodies with their throats cut," National Police chief Gen.
                  Luis Ernesto Gilibert said at a news conference in Bogota.

                  Other police sources said the agents had been beheaded but the Chief
                  Investigator's office, responsible for carrying out autopsies, said the victim's
                  throats had been slashed.

                  The policemen had been seized in fighting in Boyaca in 1998 and were among
                  more than 350 security force members who the FARC, Latin America's largest
                  surviving 1960s rebel force, have captured in combat over the last two years.

                  The prisoners have been held in rebel camps scattered across Colombia while
                  FARC chieftains try to pressure the government into exchanging them for some
                  450 jailed guerrillas -- a demand authorities have so far rejected.

                  In September 1999, the bullet-ridden bodies of four policemen were found in
                  shallow graves in the jungles of eastern Vichada province. The men died trying
                  to escape a FARC prison camp.

                  State security forces and the guerrillas accuse each other of violating human
                  rights and committing atrocities on the battlefield in the course of the
                  long-running conflict that has cost more than 35,000 lives in just the last 10
                  years.

                  The discovery of the policemen came a day after six school children were shot
                  to death in northwest Antioquia province during a nature walk.

                  Witnesses said the youngsters were accidentally ambushed by soldiers who were
                  lying in wait for a rebel column.