Prime Minister John Key in surprise resignation

John Key has announced that he will resign as prime minister of New Zealand, after eight years in the job, citing family reasons.

Calling it “the hardest decision I’ve ever made,” an emotional Mr Key said: “I don’t know what I’ll do next.”

Mr Key, a popular leader, said it was a personal decision, and later denied media reports his wife of 32 years, Bronagh, had given him an ultimatum.

He said he would not be seeking a fourth term in the 2017 election.

Deputy Prime Minister Bill English is likely to take over until the National party holds a caucus to choose a new leader.

Mr Key made the surprise announcement during his weekly press conference. He set a date of 12 December for the formal resignation.

He said his job required great sacrifices “from those who are dearest to me” and that his children had coped with “an extraordinary level of intrusion”.

“All I can say is that I gave it everything I had. I have left nothing in the tank.”

Referring to his wife, he told radio program Newstalk: “We talked about it and she likes the concept of me being home more but there was no ultimatum.”

Mr Key, who was formerly at Merrill Lynch as a foreign exchange dealer, ended nine years of Labour Party rule in 2008 when he ousted Helen Clark as prime minister.

He won a third term for the National Party at elections in September 2014.