Mr Hager's book - based on thousands of messages between Mr Slater, Mr Ede and others - claims Mr Ede ran Mr Key's dirty tricks operations which were kept at arms' length from the Prime Minister to avoid damaging his image.
Read more of the Herald's coverage today:
'Dirty Politics' book's claims over Brown affair
Slater ready with slew of complaints
One of the allegations is that Mr Ede -- working just a few doors down from Mr Key's Beehive office - covertly accessed the Labour Party's computer systems in mid-2011.
Mr Slater detailed his own incursions into Labour's system at the time but Mr Key yesterday told reporters in Dunedin yesterday that Mr Ede was not involved.
"Mr Slater's made it quite clear on his website today that it was nothing to do with the National Party," he said.
Asked about the suggestions that Labour's records of the incursions pointed to his own offices, Mr Key said: "I don't think that's right. It's nothing to do with our office."
Mr Slater and a National Party Headquarters staffer were able to gain access to Labour's records because of a security flaw on the party's website.
Mr Key suggested that even if Mr Ede had accessed the records, "of course it would be fine to go and do that" because they were unprotected.
Asked if he stood by Mr Ede, Mr Key responded: "Yeah absolutely."
Mr Ede left Mr Key's office this year and is now working at National Party headquarters on its re-election campaign.
Campaign chairman Steven Joyce early yesterday said he understood Mr Ede had not accessed Labour's records.
But he later changed his mind telling the Herald: "He may have seen it but it was wide open for anyone to see."
But like Mr Key he said: "I don't think it was a big deal either way.
"I wouldn't necessarily have done it but I'm not going to judge."
Video: Key responds to Hager book 'Dirty Politics'
Another claim is that Mr Slater was tipped off by the Prime Minister's office to ask the Security Intelligence Service for a confidential document about a briefing former Labour Leader Phil Goff had with the spy agency in 2011.
Mr Hager also claims Mr Key's office had a hand in ensuring the document was given to Mr Slater.
The release of the document was embarrassing to Mr Goff at the time because it contradicted comments the Opposition Leader had made publicly about the briefing.
An angry Mr Goff yesterday said Mr Hager's version of events was "exactly what happened". Mr Key had given the information to Mr Slater either directly or through Mr Ede.
That was "totally contrary to the very strong convention about the confidentiality of security intelligence information".
"For the minister in charge of the SIS to misuse information for political purposes means that he's actually not fit to be prime minister."
Mr Key said he was "not in the slightest" involved.
"Those decisions are made absolutely by SIS and because they had the information and Warren Tucker as the head of the SIS wanted to put that as the head of the SIS in the public domain it was nothing to do with me."
Former Act Leader Rodney Hide yesterday denied Mr Hager's claim he was forced out of the job by Mr Slater and National Party activist Simon Lusk using records of alleged improper texts sent to a woman.
