Colombian President Juan Manuel Santos is lashing out at a wave of booing over his response to a deadly attack by leftist rebels.

To shouts of "liar" and "get out," Santos was loudly jeered by dozens of spectators at a 10-kilometer run Sunday in Bogota to benefit soldiers wounded in combat. The scene repeated itself Monday during a visit to Medellin.

On Tuesday, Santos said on Twitter that he will gladly endure the hissing of his opponents if that is the price to pay to end Colombia's half-century conflict.

Frustration with Santos is rising after guerrillas killed 11 soldiers last week while they were sleeping in an apparent violation of a cease-fire declared by the rebel movement in December to facilitate peace talks taking place in Cuba.