The refusal of three GCSB staff to cooperate with a police investigation into the bureau's illegal spying on Kim Dotcom will further erode public confidence in the electronic eavesdropping agency Labour says.
Police this week released a summary of their investigation of Green Co-leader Russel Norman's complaint about the illegal spying which was revealed Inspector General of Intelligence and Security Paul Neazor a year ago.
Announcing their findings three months ago, the police said the GCSB's spying was illegal but as GCSB staff did not act with criminal intent, no one would be held accountable.
However the summary noted that three current GCSB staff refused to be interviewed by police.
Dr Norman said one of those staff "appears to have played a crucial role in the GCSB's actions in this case, yet police didn't pursue this any further despite the seriousness of this matter".
Labour MP Grant Robertson said the staff were within their rights not to speak to the Police, "but obviously it doesn't help the public's confidence in the GCSB".
"It gives the impression they have something to hide. Throughout this process with Kim Dotcom and everything that followed from that the GCSB have behaved in a way that have decreased the confidence that the public should have in them. Unfortunately this will add to that."
The GCSB refused to comment other than to say that it "facilitated requests for information" from the Police and that "decisions about whether or not to speak to Police were made by the individuals and the Bureau respects those decisions".
The Independent Police Conduct Authority is currently investigating a complaint from Dr Norman about the way the Police conducted its investigation.
Meanwhile Dr Norman also claims the Police summary suggests the GCSB was supplied with data relevant to Mr Dotcom by US spy agency the National Security Agency (NSA).
The summary revealed the GCSB received data about Mr Dotcom from another agency which was not named.
Dr Norman said it appeared the data referred to was mobile phone or other electronic communications data.
"The question is who has access to this kind of information Kim Dotcom's mobile phone data aside from the NSA?"
"It's hard to see anyone else who could have provided it other than the NSA if we're talking about Kim Dotcom's mobile phone communications or other kinds of electronic communications."
Prime Minister John Key has previously denied the GCSB gets information about New Zealanders through the NSA's data harvesting system Prism to get around a ban against spying on its own citizens.
A spokeswoman for Mr Key yesterday said issues relating to unlawful surveillance of Mr Dotcom remained before the courts.
"In these circumstances, it would be inappropriate for the Prime Minister to make any comment."
The GCSB refused to comment on the issues raised by Dr Norman.