The Prime Minister has confirmed no video footage has been deleted at the Government Communications Security Bureau as part of its handling of the Kim Dotcom case.
Labour Party leader David Shearer last week claimed a video exists showing that John Key was told much earlier than he claimed about the bureau's plans to monitor the internet entrepreneur.
Labour says a video was taken of Mr Key during a visit to the bureau while speaking to staff in the cafeteria on 29 February this year.
Mr Key has previously said he only heard about the GCSB spying on Mr Dotcom on 17 September when he was informed that it was illegal.
No video has come to light.
Mr Key said on Monday if Mr Shearer holds a recording, it can only be a version that was secretly filmed and the Labour leader is making wild accusations he can't substantiate.
"We have now confirmed that there's never been a deletion; so you don't delete things in a spy agency, you archive them. There's never been a deletion, never been a tape. They've spoken to every camera operator and they have looked at all of the logs."
But David Shearer is confident his charges will stack up against the Prime Minister regarding Kim Dotcom.
A new poll by 3 News shows that the National Party still holds a comfortable lead.
Mr Shearer denied a suggestion on Radio New Zealand's Morning Report on Monday that he had gone out too far on a claim he can't stand up, saying he believes John Key has definitely lost popularity on the matter.
Mr Shearer says his fight is not about a video, but about what the Prime Minister knew.
He says other polls have a different message from the TV3 poll and show that Labour is rising.
Kim Dotcom, a German national who has New Zealand residency, is fighting extradition to the United States to face copyright, money laundering and fraud charges. He was arrested during a raid at his mansion near Auckland on 19 January this year.