He said saying people did not expect waterways to be 100 percent pollution-free any more than they expected to be “lovin'” McDonalds every time they ate it, reports the New Zealand Herald.

Key said he did not believe the marketing slogan was inaccurate, but added that it was not to be taken literally.

“Overall, 100% Pure is a marketing campaign. It’s like … McDonalds’ ‘I’m Lovin It!’ – I’m not sure every time someone’s eating McDonalds they’re lovin’ it.

“Maybe they are, but they’re probably not every single occasion. It’s the same thing with 100% Pure, it’s got to be taken with a pinch of salt.”

He said New Zealanders had to be careful not to run the country down with research which “might not be factually correct” and that critics’ attention had focussed narrowly on the most polluted waterways.

“The vast bulk of New Zealand waterways are safe to swim in, so when they look at those statistics they look at the worst ones, they don’t measure all of them, and they measure them at the worst possible time.”.”

The heightened attention on New Zealand’s environment was the result of a tourism campaign focusing on upcoming movie The Hobbit and which described the country as the “the real Middle-earth”.

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