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Rugby heart-throb Dan Carter has unlocked the secrets of his underwear drawer and revealed tantalising details of how he wears his smalls.

In what could be music to the ears of his female admirers, the All Blacks superstar has admitted he never goes "commando", has never worn women's underwear and his Jockeys don't chafe.

The first five-eighth revealed the private details at the launch of a new brand of the underwear he has been promoting since 2003 which could make him New Zealand's equivalent of David Beckham in marketing terms.

The new 3D range will see Carter become an international ambassador for Jockey. His near-naked image, a common sight in New Zealand, will appear on giant billboards across Europe and the UK in time for the Rugby World Cup in France in September.

But the pictures are more revealing than Carter himself. At yesterday's carefully orchestrated launch, media were told the first five-eighth would not answer questions about his personal life, rugby or the Rugby World Cup.

In a brief one-on-one interview, Carter agreed he also had neither the time nor the inclination to discuss, for example, the anti-smacking bill or the US presidential election race.

"No, " he said.

So the interview was to focus solely on the underpants, then. "Yes."

What makes good underwear, according to Carter, is comfort and "you can tell straight away" if they're good. He quickly points out that the new 3D range is "right up there, the best I've ever worn".

He owns 15 or 20 pairs. In fact, he owns only Jockey brand underwear. "Honestly" he insists.

Carter, who turned 26 in March, admits he is quite a shy person off the field, but says he is having fun as a model.

He is prepared for a fresh round of ribbing from mates when his billboards go global, but "it's all light-hearted and a bit of a laugh".

The press information says: "Move over David Beckman - there's a Kiwi sporting star making a challenge on your home territory."

It was meant to read "Beckham", in reference to the former England soccer captain as well known for his modelling and promotional work as for his sporting ability.

Beckham's wife, ex-Spice girl Victoria, famously confessed her husband sometimes wore her underwear, but Carter was quick to scotch any similar talk. "No. I had never heard that."

Beckham earns an estimated $47 million a year through endorsements. Neither the company nor Carter would reveal how much the new Jockey contract is worth.