New Zealand Prime Minister John Key has dismissed accusations of "dirty politics" in the first leaders debate on television. According to reports, Mr Key called the allegations a "distraction" when he came face to face with Labour party leader David Cunliffe.

As the election in New Zealand nears, the campaign has been in the shadow of a recently published book which accuses the National party of hiring right-wing bloggers to smear opponents. Mr Key's party is currently leading in opinion polls.

The prime minister said in the televised debate that he wants to focus on other important issues rather than allegations of dirty politics. His opposition, Cunliffe, took the opportunity to raise the matter and accused Mr Key of "willful blindness." The book, written by left-wing author Nicky Hager, contained alleged emails involving the National party's former staff and a senior minister.

Mr Key told media he was not concerned about the book's release despite the fact that it contains more intelligence leaks from Edward Snowden. The prime minister said whatever alleged leaks were in the book, he didn't think they would be "embarrassing", reports said.

The prime minister said the book was released ahead of the Sept 20 election to maximise its sales. Hager's book, known as Dirty Politics, contains the leaked emails between right-wing bloggers and National Party personalities. According to Hager, the book tells the story of how "dirty politics" will "poison New Zealand's political environment." The book details the alleged email conversations of the right-wing blogger and National's former staff, including tips on how not to be caught in the act. The author said Mr Key will have some "serious" questions to answer.

Mr Key, who is running for a third term in office, has dismissed the book and brushed off the comments of critics. According to a poll by TVNZ, an online poll revealed 61 per cent of voters were in favour of Mr Key, while 39 per,cent backed Cunliffe.

The prime minister told the debate audience that he is offering a "strong and stable leadership" which had helped the country's economy improve after the global financial crisis and the massive earthquake in Christchurch in 2011.