The GCSB spy agency started an investigation into its staff last night after Labour leader David Shearer said he had been leaked information about the Prime Minister's knowledge of the Kim Dotcom case.

GCSB director Ian Fletcher issued a statement last night which appeared to debunk the claim John Key had been recorded speaking about Mr Dotcom in the staff cafeteria.

He said the Government Communications Security Bureau had made "exhaustive inquiries of its records and its IT systems and can find no audio-visual recording of the Prime Minister's visit" on the day outlined by Mr Shearer.

"An investigation has commenced within GCSB as to whether there has been any unauthorised disclosure of information, and if so, its source."


Mr Shearer said GCSB sources claimed Mr Key joked about the Dotcom case while at the bureau for a briefing on February 29 - months before he originally claimed to know the agency was linked to the case.

Mr Shearer said: "We understand there is a video."

Earlier, Mr Key told TV3 he had no memory of speaking about Mr Dotcom to GCSB staff.

Mr Key has already been forced to admit he had been briefed on the bureau's involvement in the case but had not noticed a photograph of the tycoon or heard his name spoken.