Public sector Bank of Maharashtra reported the highest number of frauds (3,893), followed by ICICI Bank (3,359) and HDFC Bank (2,319) in FY17. In terms of quantum, PNB (Rs 2810 crore), Bank of India (Rs 2770 crore) and SBI (Rs 2420 crore) fared the worst. Institutional investor Advisory Services (IAS) has said in a report that he domestic banking sector reported 12,533 frauds, aggregating to Rs 18,170 crore in FY17, "Such high quantum of frauds can be attributed to weak internal controls, which are capable of leaving an indelible dent on the balance sheet of the bank. Though the banks are paying high audit fees, it is not necessarily resulting in lower frauds, which means that the overall audit quality needs to be improved," the shareholder advisory firm said. In some banks, while the aggregate quantum is low, the average fraud size is high. This indicates that the sector needs to urgently revisit and strengthen its internal financial controls. The inability to contain frauds has financial implications. For example, in Bank of Maharashtra, the fraud amount as a percentage of total assets was 1.02 per cent. Added to a gross NPA of about 19 per cent, this means that more than one-fifth of the asset size is at risk every year due to weak controls and lack of adequate due diligence. High audit fees signal more audit checks. Yet, despite paying high audit fees, the quantum of fraud in PSBs tend to be much higher.