Does an internal audit need to be conducted by someone internal to your organisation?

We would like to pass on our gratitude to our consultant for all his hard work and advice during our 3-year re-certification and assessment against the new Standard. After seven days of auditing, we have two OFIs that the assessors have put forward from the audits. This pays testament to our URM consultant, his hard work, eye for detail and advice given, both during the audits and during all the works beforehand.