Prime Minister John Key says a possible breach of the law, following his appearance on Radio Live is a matter for the broadcaster.
The Electoral Commission has found Mr Key's programme breached the Broadcasting Act and has referred the matter to the police.
Mr Key was the on-air host for an hour long show, two months before last November's general election.
The Commission says it was reasonable to conclude listeners would regard the show as appearing to encourage or persuade voters to vote for Mr Key's party or him.
New Zealand First leader Winston Peters says John Key should have been referred to police alongside Radio Live over his pre-election radio show.
The Electoral Commission has laid a complaint against Radio Live, but no complaint was lodged against the Prime Minister.
A spokesperson for Mr Key says it is a matter for police and the broadcaster.[image:4577:half:right]
John Key was given an hour on 30 September to discuss all manner of topics, except politics.
Winston Peters says the programme was a stunt and Mr Key should also be investigated.
Mr Peters says the Electoral Commission took too long to consider the matter, and it should have been resolved before voters went to the polls on election day.
Radio New Zealand's political editor says this is the latest complaint from the election that has been referred to the police for investigation.
He told Morning Report it's important to note it's Radio Live that has been referred to the police - not the National Party or Mr Key.
Radio New Zealand's political editor understands that Radio Live was warned against airing the show, but it chose to test the boundaries without offering the same opportunity to other political leaders.
It's unclear how long a police investigation might take.
Labour says the decision to refer Radio Live to the police vindicates a complaint the party made to the Electoral Commission.
General secretary Chris Flatt complained to the Electoral Commission that the show breached the law on election programmes and advertisements.
Mr Flatt told Nine to Noon that the show encouraged people to vote for Mr Key and was clearly unfair.
The Prime Minister's office says it is a matter for the police and Radio Live and Mr Key is unavailable for comment.
Labour deputy leader Grant Robertson says giving Mr Key an hour of unfettered airtime so close to the election was completely unfair and a clear breach of the law.