Police moved on media outlets yesterday within an hour of the High Court rejecting a request to make a call on whether the "teapot tape" was a private conversation.
But a stand-off between police and Radio NZ looms as the station is adamant it will not hand over material that could compromise anonymous sources.
The court decision means the legal status of the tape remains unclear, and its release would still carry the threat of legal action.
Detectives visited the Herald on Sunday and TVNZ yesterday and collected material relating to the recording. TV3 is expecting a police search today.
Radio NZ head of news Don Rood said he had asked police for more time while the station took legal advice.
Police are seeking from Radio NZ the transcripts of an unedited interview with cameraman Bradley Ambrose, who recorded the teapot tape, and related documents including contact details.
Mr Rood said police wanted material that could reveal journalists' sources, and protecting them was "paramount".
Asked what he would do if police took legal action against the station, he said: "We will have to take a stand."
In the High Court at Auckland, Justice Helen Winkelmann said it would prejudice the ongoing police investigation if a ruling was made.
"I have not reached any view on whether this was a private communication.
The decision is a blow for Ambrose and a possible future defamation case he is considering taking against Mr Key and the National Party.
He is believed to still be considering taking a case.
If police decide that there is enough evidence to lay charges against Ambrose, the Prime Minister's claim of illegal activity would be tested in a criminal court.