Two candidates from South Island electorates are under police investigation for possible breaches of election advertising rules.
The Electoral Commission says newspaper advertisements for the National Party candidate for Dunedin North and incumbent MP Michael Woodhouse do not say who approved them.
The commission says the advertisements also were not authorised in writing by the National Party secretary.
Labour's candidate for Wigram Megan Woods is also under investigation for similar breaches made on the social networking website Facebook.
The commission says it has referred the cases to police and will not be commenting further.