The cameraman who made the "teapot tape" says his reputation is under attack, and he is considering a defamation case that could cover Prime Minister John Key, National's campaign manager Steven Joyce and Act leader Don Brash.

Bradley Ambrose, a freelancer, is seeking an urgent judgment in the High Court at Auckland on the recorded conversation between Mr Key and Act candidate John Banks.

He is asking for a declaration on whether the conversation between the pair was a "private communication" under the Crimes Act.

If the court rules it was not, it would mean the recording was not illegal.

Ambrose's lawyer, Davey Salmon, has asked for a hearing no later than Tuesday - four days before the election - and a decision could be given before election day.

In his court affidavit, Ambrose said he was taking action because he had been accused of a crime and his professional reputation was at stake.

Asked if Ambrose intended to take a defamation case, Mr Salmon said he was "considering his options".

"He strongly disputes the suggestion that he did anything unethical, or illegal, or that he intentionally recorded the conversation."

A person is defamed if their reputation is lowered in the eyes of right-thinking members of the public.

Comments about the recording have included suggestions that it was criminal and unethical, and Mr Key and Mr Joyce have compared it to the tactics of the News of the World, which provoked outrage for its phone hacking of hundreds of people, including a young murder victim.

Yesterday, Dr Brash told Radio New Zealand that the recording was "clearly unethical, almost certainly illegal as well".

Mr Key has laid a police complaint because a private communication cannot be recorded without the consent of one of the parties involved.

Illegally intercepting a private communication carries a penalty of up to two years in jail.

Under the act, a private communication is one made under circumstances that "may reasonably be taken to indicate" that the parties involved want to keep the communication to themselves.

But it does not include situations where any party in the conversation "ought reasonably to expect" that it may be intercepted with express or implied consent.

Mr Salmon said he did not believe the Banks-Key conversation was private under the legal definition.

"If you look at the pictures, a media scrum with people standing within a metre doesn't look very private, especially if you've invited them all."

In his affidavit, Ambrose said the recording was not intentional.

"Having said that, it had never occurred to me that somebody would suggest that recording was prohibited and/or that a level of privacy was required or expected.

"There were press and public close enough to hear the conversation had they tried ..."