(CNN) -- Pope Francis on Monday asked for forgiveness for the sins of church leaders who didn't "respond adequately" to reports of clerical abuse. During a Mass with six victims of clerical sexual abuse, Francis said: "I beg your forgiveness, too, for the sins of omission on the part of church leaders who did not respond adequately to reports of abuse made by family members, as well as by abuse victims themselves. This led to even greater suffering on the part of those who were abused and it endangered other minors who were at risk."