Secret documents which John Key says he made public to protect his reputation threatened massive damage to New Zealand's wellbeing if made public without permission, according to the GCSB's own threat estimates.
The four documents were made public yesterday by the Prime Minister after Pulitzer Prize-winning journalist Glenn Greenwald published claims the public were subjected to mass surveillance.
They all show they were previously marked at the "Secret" level of classification.
The GCSB guide to security classifications says the "compromise" of "Secret" information could "damage the security, defence or international relations of New Zealand and/or friendly governments".
The GCSB's threat estimate guide:
The guide spells out specific risks based on the classification, saying unauthorised release of the information posed serious risks to New Zealand including:
* causing serious damage to relations with friendly governments;
* seriously damaging the security and effectiveness of NZ forces or friendly forces;
* seriously damaging the effectiveness of valuable security or intelligence operations;
* seriously damage the internal stability of New Zealand or friendly countries;
* or to shut down or substantially disrupt significant national infrastructure.
The guide also stated that the information could be made public under the Official Information Act. "Classifications are used to grade information on the basis of the damage that would result from unauthorised disclosure and to specify the protective measures to be applied."
A spokeswoman for Mr Key refused to make public any detail as to how the documents were declassified so they could be made public. She said the steps taken - by previous statements over the course of Sunday - were "appropriate" but "we are not going to go into details of what that process involves".
She said Mr Key did not expect any of the consequences outlined in the GCSB guide to occur.
The documents were released by Mr Key to back up his claim the mass surveillance program alleged by Greenwald was cancelled in early 2012.
He told Radio NZ yesterday there was no public interest in making the information available during the debate over new spying laws last year.
"(Greenwald)'s made claims on television ... that are deliberately attempting to damage my reputation and tell New Zealanders that I'm doing something that I'm not and I've got no option but to protect myself," he told Morning Report.
Questions to the GCSB over the process for the declassification were rebuffed with officials saying the Prime Minister was handling the issue.
Greenwald targeted the release of the documents during the Auckland Town Hall event. He said the documents were either incorrectly declassified or the Prime Minister was using classified information for political purposes.
"The Prime Minister needs to be held accountable to explain to the public which of the two it is."
Labour's David Cunliffe and the Green's Russel Norman have also criticised Mr Key for the declassification.
Mr Cunliffe contrasted the declassification with Mr Key distancing himself from the early release of information from the SIS to a blogger.
An inquiry is currently underway into allegations a staff member of the Prime Minister was involved in the information being sought and released for political purposes.
In that case, Mr Key said his office had nothing to do with the release of intelligence information and that it was handled by the agencies.
Asked about Mr Key's decision to declassify information to combat Greenwald and Snowden's allegations Mr Cunliffe said that was ''a tricky one''
''Classification is supposed to be based on National interest criteria not political interest criteria for the Prime Minister.''
Shouldn't have been classified in the first place?
''I don't know what the information says so I can't give you that decision what I'm saying is the decision on classification or not should be based on the national interest not the National Party interest.''
Read the released documents here: