The story of the two New Zealand schoolgirls who exposed a multinational company's false claims about the nutritional value of Ribena has been reported as far away as Asia, America and the British Isles.

Auckland teens Anna Devathasan and Jenny Suo conducted a high school experiment in 2004, when they were just 14, which showed Ribena's ready-to-drink beverage had far less vitamin C than advertised.

The pair wrote to the company that produces the drink, GlaxoSmithKline, but say they were fobbed off, with no response to letters and only a brief reaction when they telephoned.

On Tuesday GlaxoSmithKline was fined $NZ217,500 ($A192,900) in the Auckland District Court, and has been ordered to admit in half-page newspaper advertisements in New Zealand that it misled customers.

The company earlier admitted to 15 representative charges, including falsely stating its cartoned ready to drink Ribena contained 7mg of vitamin C per 100ml when in fact it has no detectable vitamin C content.

The company claims there was never any intention to mislead their customers and removed the vitamin claims from their packaging and advertising last year.

She spoke to AAP after conducting a television interview with the BBC, and said she had been flat out fielding calls after the Ribena issue was reported as far afield as Malaysia, Canada and Scotland.

"We are just kind of numb to it all. We are really tired ... We were supposed to do CNN today as well, but they cancelled at the last minute," Devathasan said.

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