Labour plans to appeal against a ruling by the Advertising Standards Authority that attack advertisements targetting John Key are misleading.
The "two Johns" advertisements feature two images of Mr Key with different text, including the line that he wants to cut KiwiSaver in half.
The complaint said the adverts breached the the code of ethics with the statement about KiwiSaver, which was not consistent with the National Party's actual policy.
The authority upheld the complaint, noting that the claim to cut KiwiSaver in half only applied to the minimum contribution required by employees.
The advertisements have been played on television, radio and the popular internet site YouTube.
However, the authority said it only has jurisdiction over the YouTube material, as the ads on radio and television are classed as election programmes and are covered by the Broadcasting Act.
Labour Party general secretary Mike Smith said a modified version of the advertisement will play on YouTube, pending an appeal.
"We'll review it carefully and appeal within the three day process. The modifications we'll make will be slight."
National MP Gerry Brownlee says the complaint came from a member of the public, unknown to the party.
He says the advertisements should be withdrawn altogether, though he is confident the public can be trusted to make up its own mind, whatever happens.
"I suspect that there are concerned New Zealanders out there who are looking at some of the election advertising and asking the question - is this reasonable, does this add to the information stream that people need?"