Winston Peters is comparing the revelations in Nicky Hager's book Dirty Politics to the Watergate scandal that brought down US president Richard Nixon.
The book, launched yesterday, implicates Prime Minister John Key in covert smear campaigns against his political opponents.
Mr Key's office has dismissed it as a litany of unfounded allegations written by a well known left-wing conspiracy theorist.
Mr Peters says it reveals evidence of taxpayer resources being used for political attacks against the Government's foes.
"Sadly for the Prime Minister, it goes to his office in the same way it went to Nixon's office during the Watergate scandal," he said.
"This is a very dark day in New Zealand politics."
Mr Peters says it would be senseless for the Government to deny the seriousness of the situation because the emails published in the book prove the involvement of Beehive staffer Jason Ede.
Hager says the book is based on a large number of internal communications between National-aligned blogger Cameron Slater and various National Party figures.
Slater's computer was hacked and crashed after the blogger posted disparaging comments about a young West Coast man who had been killed in a car crash.
"Some weeks later, out of the blue, I received a package: an 8-gigabyte USB digital storage device, the contents of which appeared to have originated from the attack on Slater's computer," Hager says in the book.
"On the USB were thousands of documents that revealed different parts of the National Party attack politics, a subject that until then had largely been a matter of speculation and denial."
Hager says that during the 2011 election campaign, Slater obtained a database of Labour Party members and donations.
"He gleefully attacked the party. What no one knew is that Key's dirty tricks person, Jason Ede, had helped throughout, including searching inside the Labour Party computers and helping Slater plan the subsequent attacks," Hager said.
Slater said on his WhaleOil blog site on Wednesday night that he was in Korea and hadn't read the book but expected it to be "a very single-sided affair".
BOOK REVELATIONS INCLUDE:
- The PM's office used its knowledge of secret SIS documents to tip off Slater and arrange an attack on the Labour leader in the 2011 election campaign
- Mr Ede drafted Official Information Act requests for information that was passed on to Slater
- Political strategist Simon Lusk was in the loop on many of the plans that were laid
- Justice Minister Judith Collins was another of Slater's informants and emailed him an account of Labour's Trevor Mallard making a fool of himself - "You can use this if you like but just don't say it was me"
- Kiwiblog's David Farrar was also given information by Mr Ede
- Slater boasted that Mr Key had called him to commiserate over the backlash the blogger was getting after posting disparaging remarks about the man killed in a road accident.
source: newshub archive