The Prime Minister is refusing to condemn anyone associated with his Government or the National Party for anything in the Dirty Politics book, saying he does not know the details.
Nicky Hager's book, released last week, claimed senior National Party members and staff were involved in feeding embarrassing and potentially damaging information on political opponents to right-wing bloggers.
Justice Minister Judith Collins has admitted giving information about a public servant to Whale Oil blogger, Cameron Slater. The minister believed the public servant, whose name she gave Mr Slater, had leaked information to the Labour Party; he was then targeted on the Whale Oil site and received death threats.
Asked on Radio New Zealand's Morning Report programme whether Ms Collins' behaviour was appropriate for a minister, he said he did not know all the details.
"What I do know, is that it is a series of selective pieces of information, many of which can't be backed up."
Mr Key said he hadn't asked Ms Collins about the matter, and stands by her.
"At the end of the day we're five weeks out from an election, people can see that Nicky Hager's made a whole lot of things up in his book, (they) can see he can't back a lot of them up," he said.
"People can see this is a smear campaign by Nicky Hager."
He is also standing by former staff member Jason Ede, now working for the National Party, who had looked around the Labour Party's website, which was meant to be secure.
"If a left-wing blogger went around and found out that there was a situation where the security had been taken off and went and told that to, I don't know, someone who works in David Cunliffe's office, would they potentially go and have a look? Now, the answer is yes, and that would be totally fine."
Mr Key was asked if he was happy to associate himself with Mr Slater. "At the end of the day he's not my guy, Cameron Slater ... anyone who knows Cameron Slater knows that he's a force unto himself."
The prime minister said that, whether he liked it or not, social media was now part of the media network and he had to deal with it.
'No knowledge of OIA request'
The book also alleged the Prime Minister's office tipped off Mr Slater about the contents of classified SIS documents and how to request them in order to smear the then-Labour leader Phil Goff.
The book raises questions about how Mr Slater so quickly got a copy of a briefing given to Mr Goff early in 2011 from the Security Intelligence Service. It says Mr Key or his office must have been involved.
Mr Key said the Official Information Act (OIA) request did not come across his desk and did not sign off on it.
"I knew there were requests, I would have known because generally they say there's a series of requests into the SIS or the GCSB but they often sign off on, well they always sign off on, things on their own timetable. We've got slightly better processes now, so they'll tell me."
Dotcom not linked to Hagar book - Harre
Internet Party leader Laila Harre has rejected suggestions that party founder Kim Dotcom is linked to information used as the basis for Mr Hager's book.
The book is largely based on material hacked from Cameron Slater's Whaleoil website, and Mr Slater believes Kim Dotcom was the source. Both Nicky Hager and Mr Dotcom have denied that.
Ms Harre told Morning Report the situation was clear. "Nicky Hager and Cameron Slater are the two people whose evidence is out here on this source of the hacking. Who do you believe? Nicky Hager has said that the origins of the information had no association whatsoever to do with Kim Dotcom."
Meanwhile, the Internet Party leader is demanding the Prime Minister remove any responsibility Justice Minister Judith Collins has for the Electoral Commission.
Ms Harre said it was untenable for Ms Collins to remain responsible for the commission when she is so deeply involved in activities outlined in the book.