Slater said he was likely to lay a police complaint against Hager over the use of his hacked emails and messages. He also said he had texts which he alleged implicated internet tycoon Kim Dotcom in the hacking.
Hager dismissed Slater's claims about Dotcom as a "total diversion".
The author said he had met Dotcom due to a shared interest in intelligence matters. If Dotcom had offered him the information, he would not have accepted it.
Separate complaints to police would be laid by the Green Party, which has also called for a number of inquiries into the book's revelations.
The complaints would allege corruption, blackmail and unauthorised access to a computer system.
Political opponents have leapt on the book's claims today.
Read more from political correspondent John Armstrong:
Hager's claims light a fuse under the State of Key
Dirty Politics: Who are the key players?
Former Labour leader Phil Goff today said Mr Key was "not fit to be Prime Minister", while New Zealand First leader Winston Peters said the book showed National was "down and dirty".
Mr Key today said he would be happy for any investigation to be undertaken by any agency into the allegations in the book.
He again accused Hager of being a left-wing conspiracy theorist and said any actions undertaken by Slater were his alone, and not under direction of the National Party.
Mr Key denied he had any involvement in any of the allegations, adding he would not read the book until after the election.
He said Ms Collins retained his support.
Listen to Newstalk ZB's interview of Cameron Slater:
Mr Key was particularly annoyed he was said to have made offensive remarks about a West Coast resident.
"That type of speech is not me."
The book claimed Slater described West Coast woman Jo Hall as a "feral f****** b****" after having a conversation about her with Mr Key.
Slater had written a blog post in which he described Mrs Hall's 26-year-old son Judd, who was killed in a crash, as "feral".
The post lead to a widespread public backlash and a denial of service attack on the Whale Oil blog which shut the site down for three days.
It's claimed that during that time hackers obtained thousands of emails from Slater which were passed onto Hager.
Mrs Hall today described the publication of the book as "wonderful".
"I take great delight in the fact that it's all come out in the wash," she said.
Listen to Newstalk ZB's interview of Nicky Hager:
