When an internal audit team leader encounters difficulties due to the lack of a system of internal controls, the most appropriate course of action is to add a consulting component to the scheduled assurance engagement. This approach allows the internal audit team to provide advice and recommendations on establishing internal controls while still fulfilling their assurance responsibilities. By integrating consulting activities, the auditors can help the business unit improve its control environment, which can then be assessed in the assurance engagement.

The Institute of Internal Auditors (IIA) Practice Guide: Consulting Engagements

IIA Standard 1130 - Impairment to Independence or Objectivity