Air New Zealand has criticised the Australian Competition and Consumer Commission for trying to block its proposed co-operation agreement with Air Canada.
The commission is proposing to deny the airlines the authority to fly between Sydney, Auckland and Vancouver, saying it could reduce competition among the four carriers plying the route.
Air New Zealand has issued a statement saying it struggles to understand the draft decision.
It says wherever there are two or more carriers on a route, competition is intense anyway.
The commission has yet to make its final decision but Air New Zealand says it will be calling for consistency, and noting the watchdog has backed Qantas in similar route-sharing deals.