NZ First leader Winston Peters is refusing to rule out reading a transcript of the teapot tape in Parliament – and experts say there is little to stop him.

The secret recording has been credited for Mr Peters' return to Parliament. But he was tight-lipped yesterday on speculation he would raise the matter in the new term.

A political storm erupted last month after freelance cameraman Bradley Ambrose recorded the cup-of-tea meeting where National leader John Key publicly endorsed ACT's John Banks.

The tapes are under wraps while police investigate – and a court refused to rule if the conversation was private.

Shadow leader of the House Trevor Mallard believes Mr Peters will reveal the tape's contents as parliamentary privilege means he is immune from prosecution. "He wants to keep the the story alive."

A recent change to the Standing Orders – Parliament's rules – required an MP to inform the Speaker if they intended to break sub judice rules or breach a court order, he said.

However, this would apply only from the time a charge was laid.

Speaker Lockwood Smith was also unclear on whether the Standing Orders could prevent the transcript being read in the House.

"The question is: is the matter sub judice or not. Just because the police are investigating something doesn't make it sub judice, it is only if a matter is before the courts, and I'm not sure that it is."

Otago University law professor Andrew Geddis said there could be no legal consequences.

"The question is, would he have to tell the Speaker and, if he did, would the Speaker tell him not to. The reason that rule is there is to stop conflict between courts and Parliament ... Here there is no court order and, until charges, are laid it's not even a criminal case.

"The only question would be: should he do something in Parliament that outside Parliament would be illegal."

If the move was a bid to win publicity, it would be in vain if media outlets were still banned from publishing the contents.

Wellington barrister and media lawyer Steven Price said MPs were "bullet proof" but it was an "open question" if media could publish. "The police seem reluctant to prosecute once somebody has said something in the House, if all you are doing is repeating what they've said."

Mr Geddis said: "You'd have to look at what the courts have said. The thing that would come close is where MPs have said things that breach suppression orders ... the privileges committee have said there may be no protection in law for the press that does this."

- Fairfax NZ