The Electoral Commission is taking issue with Election Day coverage by state-owned television network TVNZ as well as a radio show hosted by Prime Minister John Key during the campaign last year.
The body that administers elections has referred coverage by TVNZ's One News before 7pm on November 26 to police.
The commission alleges statements that were likely to influence electors were made by One News. This is not allowed before polls close on election day.
The commission did not elaborate on what the statements were. TVNZ could not be reached for comment.
Earlier NZ First leader Winston Peters says Mr Key should be referred to the police for hosting a radio show in the run-up to the election.
The Electoral Commission ruled that Mr Key's RadioLive show breached the law and referred it to the police.
It hasn't said Mr Key did anything wrong but that isn't how Mr Peters sees it.
"He should take responsibility, it was a stunt like the tea party," he told reporters.
"Of course he should be referred to the police, he was the one essential to it happening, it was designed to get around the rules and he's been caught out."
The Labour Party, which laid the complaint after RadioLive didn't give its leader the same opportunity, says it has been vindicated.
The show on September 30, which featured interviews with the likes of All Blacks captain Richie McCaw and entrepreneur Sir Richard Branson, was aired during a three-month pre-election period when there are strict controls on campaign advertising.