The Electoral Commission has referred Mediaworks to police after a broadcaster on George FM urged people to vote for the Green Party on election day.
The commission said the Auckland-based station broadcast statements on September 20 which were intended to influence people how to vote before the polling booths closed - a breach of electoral rules.
In a statement, the commission said it also took the view that the short broadcast by George FM was an election programme, which was a breach of the Broadcasting Act.
A Mediaworks spokeswoman said the company took its responsibilities as a broadcaster seriously, and trained its staff about election day rules.
"Unfortunately on Saturday 20th September, one of the announcers on George FM was a volunteer, and was unaware of their responsibilities under the Electoral Act."