A DJ at Waikato radio station The Edge is being investigated after making a prank call during the high-security New Zealand Golf Open.

Police are investigating Iain Stables after he called a Paraparaumu radio station on January 10 - the opening day of the international event starring Tiger Woods - claiming to be a traffic safety manager.

Speaking live on Kapiti's Beach FM, Stables told motorists there was a two-hour traffic jam.

He said Traffic Safety Management recommended they relieve the boredom by "playing with themselves".

The station, which has a recording of the call, complained to police.

Programme director John Douglas said the prank had inconvenienced the public, who relied on the station for traffic information.

"I think it was a very childish joke," he said.

New Zealand Golf Open promoter David Pool said it was "a very silly thing to do at that time".

Tournament security had been stepped up after a death threat on Tiger Woods.

"Given the way the world has changed since September 11, prank calls are now taken very seriously worldwide," Mr Pool said.

He doubted gate sales had been affected because "listeners would have realised it was a prank call".

Wellington Inspector Dave Allo said police were investigating, but no charges had been laid.

Police traffic operations had not been affected.

Stables, 28, said police had advised they planned to charge him with "impersonation of a member".

"I just can't believe it. Why aren't they out there dealing with more important things?" he said.

Last May, Stables was convicted and fined $1100 for impersonating a police officer and misusing a phone after he called Los Angeles airport and pretended his work mates Jason Reeves, Clarke Gayford and Jay Jay Feeney were smuggling kiwi eggs in their "rear cavities".

And he is due to appear in court tomorrow for sentence after pleading guilty on December 9 to a charge of "assault with a bucket of water" for dousing a group of anti-vivisection protesters outside the Novotel Tainui last June.

Judge Anne McAloon indicated she was likely to fine him and order reparations.

Stables will also defend a charge of disorderly behaviour for paying a man $100 to "kiss my arse for a back stage pass" in front of 10,000 people at the Summerjam concert in Hamilton last March.

Television sports reporter April Ieremia last year sued Stables for falsely claiming she was his wife. The matter was settled out of court.