Christchurch police are fielding calls from people wanting them to shut down a bare-breasted parade promoting the three-day Erotica Expo this weekend.
A number of upset callers have complained about the "boobs on bikes" parade through Cathedral Square, scheduled for lunchtime on Friday.
But Inspector Gary Knowles said today while police understood some people would be upset about porn stars being driven through Christchurch streets on motorcycles and in open-top cars, it was a "moral not a criminal issue".
"This is not a police issue," Mr Knowles said.
"We have taken legal advice and unless there is a breach of the peace, we cannot intervene."
It was not an offence to ride on a motorcycle if the riders complied with traffic rules.
"In this case there seems to be no clear intent to offend. It is a normal ride, (so) no permit is needed."
Mr Knowles said complaints to police would not stop the event happening.
Police have been referring complaints to Christchurch City Council.
Council transport and streets manager Michael Aitken told NZPA the council had received no application for a parade.
Parades and processions were usually approved if traffic and crowd management issues were addressed.
"Council does not stop parades unless there is a traffic safety issue, and does not usually involve the police in processions except to help manage traffic and crowds," Mr Aitken said.
He said any application from Erotica Expo would be considered on those criteria.
"The standard of dress of participants is not a matter that the council can control," he said.
A council spokeswoman told NZPA staff had recorded just a handful of complaints about the parade.
Expo spokeswoman Sandy Watts told NZPA no application would be made to the council because "boobs on bikes" was a "promotional ride" rather than an official parade.
Organisers expect a large crowd to turn out for the exhibition at the council-owned Christchurch Convention Centre on Friday, Saturday and Sunday.
More than 12,000 visited the show last year and spokeswoman Ms Watts predicted up to 15,000 would attend this time.
She said Christchurch was considered more "conservative" than Auckland "but we’re expecting a lot more than last year’s attendance".
A crowd of more than 100,000 lined Auckland’s Queen St for the "boobs" ride last year after Mayor Dick Hubbard declared such a display "morally repugnant" and councillors attempted to ban the parade.
The furore in Auckland, widely regarded as New Zealand’s most liberal city, handed Erotica guru Steve Crow priceless publicity.