There is nothing in the standard that states a certification is required.
What I have seen done is a sort of job shadow. The QA Manager (who has an extensive background in ISO standards) took a newly selected internal auditor on several internal audits as a co-auditor. After x amount of hours the new auditor then performed their own audit and submitted it for review. This was used to prove competency, and the new auditor was then authorized to perform internal audits on their own.
What I have seen done is a sort of job shadow. The QA Manager (who has an extensive background in ISO standards) took a newly selected internal auditor on several internal audits as a co-auditor. After x amount of hours the new auditor then performed their own audit and submitted it for review. This was used to prove competency, and the new auditor was then authorized to perform internal audits on their own.
