Mr Key has also rejected claims by the Herald on Sunday that the recording was inadvertent, claiming it was "a deliberate action". He indicated his office was considering further action. The freelance cameraman had been working for the nzherald.co.nz website on Friday.
The cameraman's bag, with a recording device inside it, was left on the cafe table when Mr Key and Mr Banks had their cup of tea.
The cameraman later gave the tape to the Herald on Sunday. That paper's editor, Bryce Johns, said he believed the conversation was in the public interest but he would not publish the transcript because Mr Key and Mr Banks would not provide permission. No one has published the conversation.
Recording a private conversation without consent is illegal and punishable by a prison sentence of up to two years. APN, publisher of the Herald and Herald on Sunday, has a strict code of ethics which prevents publication of a conversation obtained through "illegal or deceitful" means.
Mr Johns said the cameraman was not working for the Herald on Sunday but was a freelancer from whom the paper often sourced footage.
He said the cameraman had not been given direction by the paper on Friday but had elected to give the recording - which the cameraman had not listened to - to the Herald on Sunday newsroom.
Mr Key said the discussion which was recorded was "bland" but he would not authorise its release in case it encouraged any repeats of such behaviour.
"I'm not in the slightest concerned about the contents of the tape."