Questioning the 100% Pure campaign is like questioning the Absolutely Positively Wellington brand or the I'm Lovin' It slogan of McDonald's, Tourism New Zealand says.

The national tourism agency has successfully defended a complaint to the Advertising Standards Authority laid by Fiji-based sustainable transport researcher Peter Nuttall, which was not upheld.

Nuttall laid the complaint in March and said New Zealand could be the most pristine environment in the world.

"But it ain't. Instead, we are saddled with short-term, narrow-focused profit-driven free marketeers more interested in spin-doctoring a myth to the world," he said.

His complaint was backed by controversial freshwater scientist Mike Joy, who made headlines in November when he questioned the integrity of 100% Pure.

At the time Tourism Minister John Key defended the brand saying, "It's like saying 'McDonald's, I'm Lovin' It' - I'm not sure every moment that someone's eating McDonald's, they're loving it ... it's the same thing with 100% Pure."

The agency is no stranger to defending the successful, long-running global tourism marketing campaign which has been periodically attacked from various quarters over its 14-year run.

Yesterday, Joy said the complaint had always been a "long-shot" and had been used to highlight the "fact that we're not 100 per cent pure".

The authority disagreed with Nuttall's interpretation that the 100% Pure brand was "inextricably bound to environmental factors", instead finding 100% Pure "was a positioning statement" used "to promote the unique experiences New Zealand offered international tourists rather than an absolute claim about New Zealand's environmental purity".

Tourism NZ spokeswoman Deborah Gray said the agency was never concerned about the complaint but was pleased by the outcome.

"There is no environmental claim made by the 100% Pure New Zealand campaign, meaning there was never any basis to this complaint," she said.

"Through the ongoing use of the highly successful 100% Pure New Zealand campaign, we will continue to deliver economic benefit to all of New Zealand."