Speculation about the FBI's interest in Kim Dotcom was passed across government departments and wound up in a report for ministers long before he was arrested, documents show.
Information described as "vague" was passed from one government department to another before being included in a report to Justice Minister Simon Power and Land Information Minister Maurice Williamson.
The pair were given the information in a file as they considered whether to allow Dotcom to buy the $30 million mansion he was renting.
It said there was the "possibility" the FBI "may be interested in investigating Mr Dotcom because of his ownership" of file-sharing companies.
The tip turned out to be accurate with at least four branches of government aware at least six months before Dotcom was arrested in January at the request of the FBI. He faces an August extradition hearing over charges of criminal copyright violation relating to his file-sharing company Megaupload.
He denies the charges.
Mr Power and Mr Williamson's decision to reject Dotcom's bid to buy the mansion in Coatesville north of Auckland has come in for questioning because Immigration NZ had approved Dotcom's residency under the Government's "investor" category.
The dialogue between government departments has been revealed in a document from the Overseas Investment Office obtained by the Herald.
The document had previously been released under the Official Information Act but the section relating to the FBI had been deleted.
It stated: "There is no suggestion that Mr Dotcom has personally dealt in pirated digital content. The claim was a general comment made to Immigration New Zealand's intelligence unit.
"Immigration NZ did not disclose whether or not the person who made the claim was from the FBI or whether or not that person had first-hand knowledge of the alleged FBI interest."
It stated information of "alleged FBI interest" had been "disregarded" by Immigration NZ when it granted Dotcom a residency visa. The Overseas Investment Office said the "claim of possible FBI interest in Mr Dotcom is so vague we cannot rely on it".
The OIO document then referred to a written report from Immigration NZ which stated the FBI reference was a "general comment".
Immigration NZ told the OIO the tip did not mean Dotcom was wanted for questioning, under investigation or facing charges.
Mr Williamson's office refused to say whether he knew of the FBI interest when handling the application.
A spokeswoman said all information to which the public was "legally entitled" had been released.