Key Points:

The cocktail party spy who caught out three National MPs says he is "appalled" at how easy it was to catch them talking loosely.

He says he has two hours of conversations. More excerpts are likely to come out before the election.

Kees Keizer, a Wellington 28-year-old with left wing leanings, has identified himself as the taper. He says he is not a member of any political party.

Speaking publicly for the first time, Mr Keizer said he came up with the idea to tape MPs at the cocktail party before National's August conference on the spur of the moment.

"Initially it was just seen as a bit of a joke," he said. "Obviously I was concerned about the upcoming election."

Mr Keizer said he took a digital recorder and had "legitimately" entered the conference by paying for a ticket - although he would not say what name he used.

Once Mr Keizer was in, he said he used his real full name and said he was interested in joining the Young Nats.

"I spoke to a lot of people, but obviously the useful ones have been utilised," he said.

Mr Keizer has drip-fed the tapes to TV3 political editor Duncan Garner and refused to comment when asked if there would be more before the election. Mr Garner has indicated there could be more.

Mr Keizer was born in the Netherlands but raised in Invercargill.

He has a MA in conflict resolution and since the taping has begun working for Devnet, a network that connects those involved or interested in international development. He is well-known as a top-level distance runner.

Mr Keizer said he had not edited the recordings to change the context but rather to keep his voice secret. He refused to release the full recordings so this could be tested.

He said while he had friends and connections in the Labour, including those on the Labour-affiliated website The Standard, he also had friends in National too.

The Standard is the website where a blogger calling himself Batman posted about John Key's supposed links H-Fee. That blogger is believed to be a senior official, most likely party president Mike Williams, although he has denied it was him.

Mr Keizer said he was the only spy at the cocktail party but said he received "advice" from others.

National leader John Key has blamed Labour for the tapings, but Mr Keizer said he was wrong.

"I'd like to just absolutely confirm that I'm not a member of any political party and I've not been put into this by any political party or organisation."

He said attempts to link him to Labour were "grasping at straws - and just unfortunate".

Mr Keizer recorded deputy leader Bill English talking about selling Kiwibank "eventually", which led to an apology.

This week he released a tape of Mr English talking about war, the United States, needing to have someone "willing to pull the trigger" and describing President Barack Obama as "moralistic".

Mr Keizer also caught Lockwood Smith suggesting he would like to do things in government "that may not be policy right now", and Nick Smith saying National was in "neutralise phase" before the election.

He said he was both surprised and appalled by what the MPs said.

"This is certainly in the public interest, it certainly enhances our democracy by having what politicians say in private have to come out in public, especially if it concerns policies that are good for ordinary New Zealanders, like Working for Families and Kiwibank.

"And now Obama. I think it is quite obvious that National would have sent troops to Iraq. There would have been body bags. That's not in New Zealand's interests. That's not in the public interest."

Mr Keizer was identified after bloggers David Farrar (Kiwiblog) and Cameron Slater (Whaleoil) noticed he had taken a complaint about an Employers and Manufacturers Association anti-Trevor Mallard advertisement to the Electoral Commission.

Mr Slater said he drew the attention of the National Party research unit to photographs of Mr Keizer, and said it was his understanding that the MPs had identified him off there.

Mr Slater said he worked with the taxpayer-funded National Party research unit at identifying the spy by going through the Facebook sites of Young Labour members.

Mr Keizer said his complaint about the EMA advert - made just days before the cocktail party - was not linked to Labour, but rather that he "wanted to learn more about the Electoral Finance Act and saw this as an opportunity."

He complained that the newspaper ad breached the act because it could be defined as an election advertisement and cost over $12,000 but the EMA was not registered as a third party. The commission agreed and reported it to the police.

Mr Keizer said although there is no record of a secret taping being used as a political stunt "I think it was a simple thing to do". He came up with the idea within a day, believing that the National Party had secret agendas and there was no way they could keep them secret at a cocktail party.

"I thought that the National party wasn't really being truthful with its intentions so I conducted my own form of journalism, and was quite appalled by what I heard, so clearly thought it was in the public interest to have this information released."

Mr Keizer said the recordings were "strategically packaged".

"What you heard was genuine, there was no editing specifically to have it so it was in misleading quotes."

Asked if there were any more to come, Mr Keizer said: "I don't want to comment at this stage."

Mr Keizer said he did not have to use leading questions to draw the MPs out.

"Not at all. The Obama statements were a clear example. I explained that I was interested in European politics, and all of a sudden English started talking about Obama and was heavily critical of Obama. Again, linking to the Iraq war, it's just a tragedy."

Mr Keizer said he would not be releasing the entire tape.

"Most of it is useless. It wouldn't do any credit to anyone."

Asked if he was a radical, Mr Keizer said: "I wouldn't say I'm radical at all."

Mr Keizer would not identify who he voted for, but defined his politics as: "I choose a party that I think best serves the interests of the country."

"I'm certainly not a National Party supporter. I wouldn't affiliate myself with any New Zealand political party, but I certainly don't agree with the general right wing."

He identified "targeting tax relief to people that most need it rather than the right wing approach" as a policy he favoured.

His major interest was in "international relations, conflict resolution, peace and conflict". He has researched the role of the European Union in monitoring peace in Aceh since it was hit by the 2004 Indian Ocean tsunami.

Although he has travelled extensively around the world, his position at Devnet in his first in the field.

Mr Keizer said his family was not "overly political" although his mother Doetie is a prolific letter writer to the Southland Times on various issues.

He did not want to go public, but wanted his motivations and the fact in the public domain.