On at least six occasions over the course of 16 years, SEC investigators caught Madoff in a number of "lies and misrepresentations, but failed to follow up on inconsistencies," according to a new report by the agency's inspector general obtained by Reuters.

The latest investigation by the inspector general "makes clear that the agency missed numerous opportunities to discover the fraud," SEC Chairwoman Mary Schapiro said in a statement. "It is a failure that we continue to regret, and one that has led us to reform in many ways how we regulate markets and protect investors."

According to Reuters, the Senate Banking Committee will consider the report at a hearing scheduled for Sept. 10.