A Whangarei District councillor who had to resign because she does not hold New Zealand citizenship could face prosecution.
Electoral officer Dale Ofsoske has laid a complaint with police that Jayne Golightly wrongly stated she was a citizen when she first stood for council last year.
Candidates for election in a council or community board must be New Zealand citizens.
Ms Golightly was born in the UK and uses a British passport, but said she did not know she was not a New Zealand citizen until someone tipped off the Electoral Office.
Mr Ofsoske said making a false declaration was an offence under the Electoral Act and he had no choice but to report it.
"It'll be over to the police as to whether they take it further," he said.
He said it was extremely rare for an electoral officer to have to take such a step.
"I've been running elections now for about 33 years, and (for me) this is the first time this has arisen," he said.
It was irrelevant that Ms Golightly did not know she was not a citizen.
"On the nomination paper there is a place where the candidate ticks that they comply, that they're a New Zealand citizen and a parliamentary elector and both of those were ticked on her nomination form," Mr Ofsoske said.
The Electoral Officer said he rang Ms Golightly to inform her he had to report the matter to police and she was upset, but accepted his explanation.
He said the former Whangarei councillor was expecting to gain her New Zealand citizenship this week, after making an urgent application, and told him she was planning to stand again for council in the by-election triggered by her resignation.
Nominations for the Denby ward close on 11 October, and the by-election is set for the 7 December.