MANILA, Philippines -- The military has been instructed to go on ``heightened alert'' in southwestern Mindanao, particularly in Sulu and Basilan, to prevent a repeat of Saturday's attack by Abu Sayyaf bandits on a community in Basilan that left 11 people dead.

Deputy Presidential Spokesperson Gary Olivar announced on government radio station dzRB that the attack was made in retaliation for the military's recent assault and killing of Abu Sayyaf leaders led by Albader Parad.

``The people should be more careful because retaliatory attacks have happened because of the successful pursuit of their group and the killing of one of their top leaders. But they should not be alarmed because the military and police readiness level is higher to protect them,'' Olivar said.

In a statement, he said the military was directed to go after the perpetrators and to assist families affected in last Saturday's attack on a village in Maluso, Basilan, said to be the worst attack on civilians in nine years.

Abu Sayyaf bandits killed a government militiaman and 10 civilians in Saturday?s attack. The victims were sleeping when their homes were strafed by bullets and the buildings were later torched. Seventeen other people were hurt.

The attack came hours after the military recovered three Chinese factory workers seized by the Abu Sayyaf over three months ago. It also came after a string of victories by security forces against the Abu Sayyaf, including the capture of a top bomb maker and the killing of one of the group?s commanders last week.