Racing legend Sir Patrick Hogan's bid to get votes for NZ First is under scrutiny by electoral officials because of an advertisement in a racing newspaper.
In September Hogan and wife Lady Justine Hogan took out a full-page advertisement in The Informant urging the racing industry to support NZ First because of its racing policies.
The Electoral Commission said it had not received any complaints about the ad but was looking into it.
Under electoral rules, anyone who publishes an advertisement encouraging others to vote for a political party must get written authorisation from that party and the party must include the cost of it in its election expenses return.
NZ First's return did not list anything in the section requiring "third party" advertising to be disclosed.
A spokesman for NZ First said its return was accurate. "The New Zealand First Secretary did not authorise any third party advertisements."
Andrew Geddis, an electoral law expert at the University of Otago, said if Hogan took out the advertisement without getting approval it amounted to an "illegal practice" under the Electoral Act, which was a fine of up to $10,000 if there was a conviction.
He said if NZ First had authorised it but had not disclosed it in its return, it had filed a wrong return which was also considered an illegal act under electoral laws.
"So on the proviso that Hogan did place that as an ad in The Informant, someone has committed an illegal practice here, either Hogan or NZ First and the Electoral Commission has a statutory obligation to investigate such matters and to report them to the Police unless they believe it's not in the public interest to do so."
Hogan is yet to comment. He is a long-time supporter of NZ First and leader Winston Peters.
The editor of The Informant, Dennis Ryan, confirmed Hogan had submitted and paid for the advertisement which ran separately to a news story on NZ First's racing policy in the same edition.
In an article in North and South after the election, Hogan said he had helped NZ First leader Winston Peters develop his racing policy. He has pushed for a doubling of stake money and a clean-out of the Racing Board.
Peters is now Racing Minister as he was from 2005 to 2008. This year's Budget included tax breaks for horses which were brought for the purposes of breeding.
It is not the first time Hogan has taken out advertising for NZ First. In 2005 he also took out newspaper advertisements that he estimate cost from $8,000 to $12,000 in support of the NZ First party which were also not disclosed at the time because Hogan had believed that was not necessary.
Hogan also donated $12,000 to NZ First in 2008.
The advertisement used in 2017 is still on the Cambridge Stud website and has the NZ First logos on it. Hogan has since sold Cambridge Stud.
The advertisement carried the Cambridge Stud logo and began by stating Sir Patrick and Lady Justine "place their support with Winston Peters" before referring to NZ First MP Clayton Mitchell's press release supporting an all-weather track for racing.
It ended by saying "There is only one horse to back, New Zealand First, it has the race record. It is now imperative that you all take this opportunity to have what we want by making our party vote in favour of New Zealand First."
At the bottom was a large banner saying "Place your party vote to New Zealand First."
Hogan also issued a press release with similar wording which is still on the Cambridge Stud website.