IAG says it's "in dispute" with Suncorp over the acquisition of the outstanding 50% of leading truck insurer NTI.

The company was formerly owned 50/50 by IAG and Vero, and it's understood that under the terms of the joint venture agreement the purchase of Vero by Suncorp last year allowed IAG to take full ownership.

However, IAG CEO Michael Hawker told analysts on Friday that Suncorp doesn't see it that way and wants to retain the Vero stake in NTI.

"IAG haven't been able to come to an agreement with Suncorp to buy the other 50%," he said. "We're assessing our options in terms of how we move forward."

Mr Hawker says IAG believes it has a right to purchase the shareholding.