New Zealand First leader Winston Peters has lashed out at a media report tonight alleging he was out for "utu" against the National Party.

The report on Newshub said National launched a "four-pronged attack" on Peters - and now the kingmaker was out for revenge.

Newshub political editor Patrick Gower claimed his source was a New Zealand First party insider.

However, Peters hit back quickly, saying "whatever Patrick Gower and the Newshub producers are on, they should get off it".

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"Their TV news broadcasts the last two nights have been fiction, and grossly misleading. I will not be explaining what parts are fictional. Some of it is barefaced lies.

"This news broadcaster is claiming sources that don't exist. It's the very worst form of journalism," he said.

"None of it will have any bearing on New Zealand First in the coming talks around the establishment of the next government."

In an opinion piece tonight, Gower said Peters was particularly resentful toward Finance Minister Steven Joyce, who he "personally detests".

National's alleged four-pronged attack started with pinching NZ First's policies including boot camps, benefit sanctions, being tough on crime and increasing the speed limit to 110km/h.

The second move was to squash the party vote for NZ First, aiming to put the party below the 5 per cent threshold, Gower said.

National was also conspiring to oust Peters from the Northland electorate, replacing him with National candidate Matt King - a plan which was successful, but ultimately did not keep Peters out of Parliament.

Finally, Peters believed National was behind the pension over-payment scandal back in August.

Prime Minister Bill English has denied the leak came from his chief-of-staff Wayne Eagleson.

Investigations into the Ministry of Social Development, Inland Revenue and Ministerial Services, which manages staff in the Beehive, all failed to identify who was responsible.

National MPs Anne Tolley and Paula Bennett were both potential suspects with their portfolios covering the departments involved.

Now, Gower is claiming Peters wants utu - revenge.

In her own opinion piece tonight, Herald political editor Audrey Young wrote: "Good on Winston Peters for tonight calling out some of the drivel that has been passing as news over the past few days.

"The notion that Peters would be seeking revenge on National for regaining the Northland seat is ridiculous."

While the New Zealand First leader may have plenty of reasons for seeking revenge, losing Northland was not one of them, Young said.

"The notion that Bill English exhorting voters to "cut out the middle man" [Peters] and vote for National was some kind of dastardly conspiracy against New Zealand First is laughable. It's called an election."