Kim Dotcom has revealed to ONE News the big international name who will play a role in the bombshell he'll drop on the prime minister.

He says WikiLeaks founder and fugitive Julian Assange, who's holed up in Ecuador's London embassy, is set to take part in a pre-election attack on John Key.

"I can give you a hint. Someone who is currently locked up in an embassy might be on a live video link," Mr Dotcom said.

Mr Dotcom had warned something big will come out on September 15, just five days from the election.

He has already hired journalist Glen Greenwald, who made public the Edward Snowdon leaks. Now the addition of Mr Assange confirms the September 15 event will be about New Zealand's spying.

Asked will September 15 do more damage to Mr Key than the Dirty Politics book has, Mr Dotcom said: "I think so."

Mr Dotcom is doing damage control of his own right now following yesterday's tirade to media from Internet Party press secretary Pam Corkery.

Mr Dotcom told ONE News Ms Corkery is safe in her job with the Internet Party and with its leader Laila Harre.

"You know, she apologised. I made a funny tweet about it today saying Pam's office has done something unwise and that she is on her final, final, final warning" he said.

Ms Corkery's abuse was the result of media attempts to question Mr Dotcom about potential links to the Whaledump hacker after this comment by Dotcom yesterday: "I hacked our German credit ratings system and put our prime minister's credit rating to zero because I didn't like the guy. And you have all figured by now there's another prime minister I don't like."

Asked today does he have anything to do with Whaledump, Mr Dotcom said: "Absolutely not."

And September 15 won't be the only showdown between Mr Dotcom and Mr Key in the election campaign. The Internet Party will hold its election night function at The Cloud on Auckland's waterfront with Mr Key and National just a few hundred metres away at the Viaduct Events Centre.

Key 'far more prepared'

ONE News political editor Corin Dann says the involvement of Julian Assange in Kim Dotcom's September surprise certainly ramps things up.

"He is a big figure, of course co-founder of WikiLeaks. That's going to draw international attention in itself," Dann said.

But he says he thinks John Key is "far more prepared" for revelations of spying and that Mr Key believes the public will be reasonably forgiving if there are some embarrassing leaks about New Zealand's spying activity.