The SIS has issued a blunt response to information published by a newspaper on a New Zealander accused of spying for the Russians.
The Dominion Post reported on Monday it had new information from a now dead Soviet defector claiming the late Bill Sutch really was a Soviet agent, despite being cleared by a court
Dr Sutch was a high flying civil servant, who headed a major Government department.
He was accused of being a Soviet agent but acquitted after a trial in 1975 and was formally exonerated of suspicion by Helen Clark when she was Prime Minister.
The Security Intelligence Service (SIS) never accepted his innocence and has responded to the new information with the single line: "It speaks for itself."
The Dominion Post said the latest information came from the Soviet KGB defector Vasili Mitrokhin, who fled to Britain in the 1990s with a huge archive of KGB material. It said the new material indicated Dr Sutch was a KGB recruit working under the codename "Maori".
However, his daughter, Helen Sutch, said on Monday that the documents prove nothing.
"It's still simply an allegation by KGB agents who presumably had every interest in trying to impress his bosses at home - because nasty things tended to happen to them if they didn't deliver. So I don't think that it really is significant in any way."
Ms Sutch said it's distressing that people are continuing to make accusations about her father long after his death.
But Kit Bennetts, a former SIS agent involved in Dr Sutch's arrest, believes the documents are compelling.
"It's very clear and the use of the word 'recruited' in there shows that he was a recruited asset from 1950, which was about the time that there was serious concerns about him. Yes he's not named, but you wouldn't expect him to be named. His codename Maori is used. All the biographical detail exactly fits."
The Sydney Morning Herald quoted the Mitrokhin material as saying a 20-year Labour Party MP in Australia, Albert James, was also a KGB agent.