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"This is an unexpected medical event and of course unexpected timing. However the doctor's advice on having surgery needs to be followed," said Peters.
Following a brief hospital visit Peters, 75, will have a post-operative period of recuperation at home, a statement said.
"I remain confident of a quick return to work - as well as being fighting fit for the election campaign, which is typically physically gruelling," said Peters.
The unexpected medical leave means New Zealand First will combine its campaign launch with the party AGM on July 19.
The party's bid for electoral seats in Northland is launching this Sunday, spearheaded by Northland and Whangarei candidates Shane Jones and David Wilson
The latest 1 News Colmar Brunton poll had the party on 2 per cent, but Peters dismissed this at the time as "rubbish".
"Stand back and watch, and see what's going to happen," Peters said in response to the poll at the end of June.
New Zealand First usually does better on election day than in the polls.
Peters was on 2 per cent support in the preferred Prime Minister stakes in that same poll.