New Zealand First is lodging a police complaint over what leader Winston Peters says is a massive breach of the party's information.
Peters says the media is using stolen information as its source for stories which he says are designed to skew the political playing field.
"This morning I have recommended to the New Zealand First Party President that she begin preparing a complaint to the police over the massive breach of New Zealand First's party information," Peters said.
"Ongoing media stories using as their source stolen information are designed to skew an even political playing field.
"New Zealand First has so far been sensitive to the circumstances surrounding the theft of party information but can no longer tolerate the mendacious attacks against the party and its supporters," Peters said.