It is understood the report finds information Dr Tucker gave to the Prime Minister's office and which was released to Slater was edited in a way that highlighted content about the suspected Israeli agents when that material was only part of what Mr Goff was briefed on.
The report is said to criticise Dr Tucker for presenting the information in a way that was incomplete, lacked professionalism and risked giving the impression of political bias.
It is understood the report recommends the SIS apologise to Mr Goff and that Dr Tucker's replacement, Rebecca Kitteridge, will do so this morning when the report is released.
Both Mr de Joux and Mr Ede have left Mr Key's office. Dr Tucker stood down as SIS director in May this year.
New Labour leader Andrew Little said Mr Key had been "tripped up" by his "smear machine".
Speaking to Radio New Zealand this morning Mr Little said Mr Key owed his colleague Mr Goff an apology.
"Irrespective of where the apologies come from in the SIS, actually there needs to be an apology from John Key for the state apparatus being put in this position," he said.
He added: "An apology just from the SIS is not going to be enough. The report will detail what the issue is there and if they need to make amends.
"The reality is this whole situation arose because John Key decided six years ago to set up a smear machine in his office.
He's been tripped up by it now on a number of occasions, this is just one. It is he who needs to apologise to the public of New Zealand for allowing his office to be used in this way.
"What has happened in John Key's office in the last six years is unprecedented in my view, he needs to step up and take responsibility, he can't duck and shove it away and say, 'SIS, it's your responsibility'. It all happened out of his office and he's got to take responsibility."
Neither Mr Key nor Mr Goff would comment ahead of the release of the report but Greens co-leader Metiria Turei said it appeared the report proved Mr Key's office was involved in dirty politics "and abused their power to manipulate at least one election campaign".
If reports on what Ms Gwyn had found were accurate, "then it shows John Key's office was involved in the deliberate smear campaign against Phil Goff and Labour and using SIS-provided information to do so.
"What this goes to is John Key's office misusing its power and authority with the SIS for deliberate political attacks against its opponents.
"The findings are so serious that a Royal Commission of Inquiry should be held into all the allegations of abuse and misuse of power in the book Dirty Politics," said Ms Turei.
Slater yesterday refused to comment saying only, "I don't talk to the Herald." Mr Ede has gone out of his way to avoid media since Dirty Politics was published in August.
What was Goff told?
July 24, 2011
Prime Minister John Key says the Security Intelligence Service briefed Opposition leader Phil Goff about the behaviour of Israeli nationals in Christchurch. Mr Goff tells SIS director Dr Warren Tucker that he had not been briefed.
July 25 Mr Goff and Dr Tucker meet to discuss the matter.
July 26 Blogger Cameron Slater asks SIS for copies of briefing notes, documents or diary notes relating to any briefing for Mr Goff about the issue, and the information is declassified the same day.
July 27 Under the "no surprises policy", the SIS tells Mr Key's Beehive office it intends releasing the information to Slater.
August 1 A media organisation also requests the same material.
August 2 Slater tells his friend Aaron Bhatnagar he had asked for the briefing minutes and notes for Mr Goff's SIS briefing and "it has been expedited in the public interest ... it is devastating for Goff, I am told". The material is posted to Slater the same day.
August 4 Slater releases the SIS information in a blog post in which he says the documents prove Mr Goff "lied about not being briefed". The same day, the media organisation receives the material from the SIS.
August 13, 2014 Nicky Hager's Dirty Politics alleges the Prime Minister's communications adviser Jason Ede was involved in encouraging Slater to ask for the information.
August 20 The Inspector-General of Intelligence and Security, Cheryl Gwyn, announces an inquiry into Hager's allegations.