Radio New Zealand, a government-owned broadcaster have refused a request by the police to surrender material relating to a cameraman who Key said taped the conversation unlawfully.

Key complained to authorities that a conversation he had with ACT Party candidate John Banks on November 11, was unlawfully taped.

The conversation took place in an Auckland coffee shop where Key went to endorse of a party that could be an ally in parliament.

Media were filming the event, but told to stop when the conversation took place.

According to the website of TV3 News, the discussion contains adverse comments about ACT leader Don Brash and the elderly supporters of the New Zealand First Party.

However, Auckland-based newspaper, the New Zealand Herald, which apparently received the tape from the freelance cameraman, has refused to disclose details of the conversation.

Jon Neilson, a police spokesman, said police are in the process of serving search warrants on the Radio New Zealand, plus three other organisations that have not been revealed.

Don Rood, head of news at Radio New Zealand, said the broadcaster would seek legal advice if necessary. “What we’ve got is in the middle of an election campaign, in an open democracy, where the country’s only pure public service broadcaster is about to be raided by the police after a complaint by the prime minister. That’s not good,” said Rood.

Opinion polls suggest Key’s government will win the November 26 election, but this latest investigation is said to be diverting attention from economic policies in the lead up to the vote.

The government, which is run by Key’s National Party, is seeking a second term, and had 53 percent support in a poll of 1000 people.

It is well ahead of the opposition, the Labour Party, which polled 26 per cent.

Public support for Key, a former head of foreign-exchange trading and European bonds at Merrill Lynch & Co., has hardly waned since he was elected in 2008.

The support for him was steadfast, even after New Zealand endured earthquakes, recession and its first credit rating downgrade in 13 years.

“It’s a horrendous own goal,” Jon Johansson, a Wellington-based political scientist, told Bloomberg. “A big part of the explanation for his tail wind ever since he’s been leader is the really quite generous media coverage that has accompanied him. You start breaking those relationships up and you watch how it all changes.”

Police have warned that unlawful recording incurs a maximum penalty of two years in jail.