From Herald Wire Services

BOGOTA -- Colombia's top paramilitary leader has acknowledged that his forces have been violating a unilateral cease-fire declared more than a year ago but blamed the violence on leftist guerrillas.

Carlos Castaño, the commander of the right-wing United Self-Defense Forces, or AUC, said in a communiqué released Saturday that his troops had no choice but to defend themselves against the rebels in areas where government troops are unable to maintain security.

''We must accept that we have been unable to unilaterally comply with the cease-fire because our organization is in the midst of a conflict in which the guerrillas have never ceased their aggression,'' Castaño said.

Government officials and the U.N.'s top human rights representative sharply denounced the AUC this week for killings despite their December 2002 pledge to cease hostilities.