After the audit report has been issued, someone discovers that the auditee had a material, unrecorded bank

Question:

After the has been issued, someone discovers that the auditee had a material, unrecorded bank loan outstanding at year-end. There was no confirmation requested from that bank as the auditors were not aware of the auditee’s relation with that bank. What steps should an auditor should take in this situation?

Audit Report
The audit report is issued by a certified public accountant who is appointed by the shareholders to provide assurance upon the truth and fairness of the financial statements prepared by the managers of the company. Audit report contains the...