The Labour Party is levelling fresh claims about the Prime Minister John Key's knowledge of the internet entrepreneur Kim Dotcom.
Mr Key has previously said he only heard about the Government Communications Security Bureau spying on Mr Dotcom on 17 September this year when he was informed that it was illegal.
A report by the Inspector-General of Intelligence and Security found that the GCSB relied on incorrect police information about Mr Dotcom's residency, believing him not to be a resident, and did not check further when it intercepted his communications.
Labour said on Thursday it has been told by unnamed sources within the spy agency that a video recording may exist in which John Key refers to Kim Dotcom.
It says that may have been recorded while Mr Key was speaking to bureau staff in their cafeteria during a visit on 29 February this year.
Labour leader David Shearer told Radio New Zealand's Checkpoint programme on Thursday the situation raises further questions about the Prime Minister and the Kim Dotcom affair.
"Either he's not completely coming forward with the truth, or he's not able to remember, or something else is going on that I can't quite put my finger on.
"But certainly, it really does cut to the credibility of John Key and his explanations on Kim Dotcom."
Mr Shearer says the Prime Minister should allow GCSB to release any and all unclassified material about the visit and his comments to staff to clear the matter up.
"Our sources are saying that there was a video made. We have simply asked for that video to be made public."
John Key says he did go into the staff cafeteria, but doesn't recall raising Mr Dotcom with members of the staff.
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.
Spy agency investigating, but 'no Key video'
The Government Communications Security Bureau on Thursday night launched an investigation into whether information has been leaked to the Labour Party - and if so, who it was.
GCSB director Ian Fletcher says the agency has conducted an exhaustive search of its records and IT systems and can find no audio-visual record of the Prime Minister's visit on 29 February.
Mr Fletcher says there were some still photos, but they will not be released as they identify staff.
He says an investigation is now underway as to whether there has been "an unauthorised disclosure of information".