"We've got it for sure until 2018," Snedden told Newstalk ZB's Tony Veitch this afternoon.
"Duco has a five-year contract with the NRL. Has support of ATEED for that time.
"I have no doubt that at the end of that time or a year or two before, Melbourne and Brisbane will both be thinking really hard about how they can pinch it from us.
"We've got to make sure every year is a winner. And secondly, together with ATEED, we have to make it so hard for the NRL to take it elsewhere."
The news comes three weeks after Aussie league officials stole this year's centenary Anzac Test from Auckland, and was last night met with outrage from league fans. Sir Peter Leitch told would-be bidders to "piss off".
Promoters Duco Events and Auckland Tourism, Events and Economic Development have a five-year contract with the NRL to host the tournament, the brainchild of the Auckland-based promotions company. Ateed has paid $10m for the event.
Snedden was unaware of the work being done by Aussie cities interested in pinching the Nines, but wasn't surprised to learn of their attention.
"I don't have any doubt that at the moment Melbourne and Brisbane, in particular, will be looking at this event and thinking, 'Is there a chance that we could actually secure this event in our city?'
"I'm not criticising them; if I was sitting in their seats I'd also be thinking that."
Both cities would be keenly aware of the economic benefits the event brings, he said. Last year it contributed 68,000 visitor nights in Auckland hotels and attracted 22,000 visitors, including more than 6,000 from Australia.
A Tourism and Events Queensland spokeswoman confirmed the body was constantly looking to secure prime events. A Victorian Major Events Company spokesman said: "When you think of a major sporting event like the Nines it is obvious why you'd think of Melbourne. We're one of the world's truly great sporting capitals, we're a major events mecca and we're open for business."
An outraged Sir Peter, patron of the New Zealand Rugby League, said officials trying to poach the Nines should "piss off".
"They [Brisbane and Melbourne] should come up with their own bloody game - don't steal ours."
Former Kiwis captain Hugh McGahan was outraged when the Aussies stole the Anzac Test, saying then: "It just proves further how much the Australians control the game without much thought at all of other countries."
On Friday he said the attempt to poach the Nines was "very disappointing".
"The Australian rugby league fraternity often disregard New Zealand. As long as there's money in it, they will milk it to its capacity."
The NRL said it was not in talks with any cities regarding future hosting rights.
