The relationship between the Government and "the sordid workings of Hollywood" will form a key part of Kim Dotcom's highly anticipated announcement on Monday - billed as the Moment of Truth.

But Dotcom is already dampening down expectations, saying he is unsure whether the revelations - including New Zealand's role in mass global surveillance and whether John Key lied over when he first knew about Dotcom - will damage the Prime Minister's credibility or convince voters to change the Government.

Dotcom mused that the apparently limited impact of Nicky Hager's book Dirty Politics on Mr Key's popularity meant that the Prime Minister could probably be photographed "shooting little kittens in his garden with a shotgun", and still be popular.

The Internet Party revealed for the first time yesterday that the event, scheduled for the Auckland Town Hall on Monday at 7pm, will include information about "the sordid workings of Hollywood".

A party spokesman did not want to elaborate or comment on whether it might involve Hollywood studio lobbying on anti-piracy measures, or the labour law changes that the Government made over The Hobbit movies. Special guests for the event include international human rights lawyer Robert Amsterdam, Wikileaks founder Julian Assange by video link, and Pulitzer Prize-winning journalist Glenn Greenwald, who has reported widely on global mass surveillance, based on classified documents leaked by Edward Snowden. Dotcom told the Herald he would present "absolutely concrete" evidence that Mr Key knew about him earlier than the Prime Minister had claimed.

But Dotcom is unsure how the public will react, especially following the fallout - or lack of fallout - from Dirty Politics.

"When I read Nicky Hager's book, I thought, 'It's over for John Key'. I didn't think the New Zealand public would put up with something like that, and I'm really surprised how little impact the book had.

"If he survived that, he could probably survive shooting little kittens in his garden with a shotgun, even if there is picture evidence of that. It's a mystery. I can't understand it.

"Will what I present change the election result, or cause serious damage to the Prime Minister? I don't know. It should."

Mr Key told TV3's Firstline today he had not lost "a moment's sleep" over the upcoming announcement.

"He's just another guy that wants to throw a bit of mud, he's just another guy who wants to create a conspiracy theory."

A photo has emerged of Mr Key's son Max at a nightclub with Dotcom's former wife Mona.

Mr Key said his son did not realise who the woman was at the time the photo was taken.

"But I don't know whether that would have stopped him or not. I wouldn't care anyway - he's 19 years of age and he goes to clubs, she was out there as well."

A Herald-DigiPoll survey this week showed just 7.2 per cent of people are certain Dotcom will produce the evidence he is promising, while 11.5 per cent believed he will not. More than 70 per cent said the information would be open to different interpretations.

- Additional reporting APNZ

- NZ Herald