Several "fake urine" products have gone on sale in New Zealand as employees attempt to beat workplace drug tests.

One, called QCARBO32, offers a "100 percent pass rate" with a money-back guarantee, the New Zealand Herald reported today.

Paul Fitzmaurice, from New Zealand's Environmental Science and Research agency, said the fake urine was difficult to distinguish from the real thing.

The owner of one company selling the products, Chris Fowlie, said the fake urine gave people back their privacy.

"Random drug testing goes against the Bill of Rights and the Privacy Act, and violates the natural justice of presumption of innocence," he said.

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