Authorities say leftist rebels killed six soldiers who were on patrol in a rural district of southwestern Colombia.

Cauca state security chief Sebastian Silva says insurgents from the Revolutionary Armed Forces of Colombia apparently attacked the troops with grenades just after midnight Monday as they were resting.

Silva says they were patrolling an area near the towns of Piendamo and Morales where rebels frequently blow up electrical towers.

At least 28 Colombian soldiers have been killed this year according to an official count.

Armed forces chief Gen. Freddy Padilla said last week that 286 Colombian soldiers were killed in action last year, nearly half by anti-personnel mines.