A man who turned up at an Anzac Day service claiming to be an NZSAS soldier has admitted he's a fake.

Rob Clark was photographed at the Takapuna Grammar dusk service last week, wearing an SAS beret, regimental tie, and 15 medals showing service.

He also wore a copy of the United States Navy Presidential Unit Citation - upside down.

The 43-year-old now admits he was an imposter, and what he did was very stupid.

Mr Clark said he's well aware he could be prosecuted.

He's also admitted that for years he has allowed people to think he was in the elite military unit.

In fact, his military record was a few years in the New Zealand Army in the early 1990s and he's had no postings abroad.

Mr Clark says he bought the medals online and the US Presidential Unit Citation is a fake a friend made during a drunken evening.

The act of wearing medals which have not been earned is prohibited under the Military Decorations and Distinctive Badges Act 1918.

If convicted under the act, a 500 dollar fine and a prison sentence of up to a month can be imposed.