International Rugby Board chief Mike Miller warned on Tuesday that price gouging during the Rugby World Cup threatened to sully New Zealand's reputation with international tourists.

The September 9-October 23 tournament will be the largest event staged in New Zealand, attracting some 85,000 overseas fans, but Miller said he was concerned about tourism operators looking to cash in.

"Some have thought 'we can make a bit of a killing here and not worry about what's in the future'," Miller told Radio New Zealand.

"It's not great for the image of the country."

There have been reports of some New Zealand motels significantly inflating their prices during the event, including one in Auckland that is charging almost 10 times its normal room rate.

Miller said tourists would always pay premium prices during events such as the World Cup but it was disappointing some accommodation providers were pushing the limit.

He said small operators were the worst culprits, with large hotel chains realising the damage that rip-off prices would inflict on New Zealand's reputation.

"They understand that a lot of people are coming to New Zealand for the first time," he told the New Zealand Herald.

"If they have a great time and feel they were getting decent value, they'll come back again. If they don't, they won't."

Miller said the New Zealand government and tourism industry bodies appeared powerless to take action.

"There's no legislation. You can't stop them," he said. "The trade organisation really doesn't have any sanctions against them except trying to get them to see it's not in their interests or the country's.

"For the most part, things are fine but there are some people taking advantage and it's very disappointing."

New Zealand Prime Minister John Key and Rugby NZ 2011 chief executive Martin Snedden also warned last year against exorbitant pricing.

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