Opposition parties continued to question Prime Minister Helen Clark's honesty yesterday and compared her to disgraced former United States President Richard Nixon.

National's deputy leader Gerry Brownlee said it was an unanswered question whether Helen Clark lied to the Sunday Star-Times over former Police Commissioner Peter Doone.

Act leader Rodney Hide went further and accused her of lying, which was ruled out of order after objections from Labour MPs.

He pointed out a phrase Helen Clark had used in Parliament the previous day: "It is a matter of judgment for the Prime Minister how I use information from official reports; by definition I cannot leak."

Mr Hide quoted from an interview Nixon gave to British broadcaster David Frost in 1977 about monitoring activities in which he said: "When the President does it, that means it is not illegal."

Frost: "By definition?"

Nixon: "Exactly, exactly."

National leader Don Brash, who has been unusually confident in the House this week, accused Helen Clark of adopting the Nixon approach.

The Prime Minister has been under sustained attack in the House about conversations to the newspaper in January 1999 before it ran a story saying Mr Doone said to a constable approaching his partner with a breath-test device, "that won't be necessary".

The newspaper apologised and retracted the statement.

The official reports into the incident conclude that he said: "We'll be on our way," or words to that effect.

Mr Brownlee insisted that Helen Clark held transcripts of conversations she had with the journalists - which she has denied - and challenged her to release them.

"If it takes us days, if it takes us weeks, if it takes us months to drag some responsibility for this issue out of the Prime Minister, then so be it.

"The unanswered question in this Parliament right now is did Helen Clark tell a lie to the Sunday Star-Times?"

The question remained unanswered after 35 questions in the House over the past two days.

"Instead we've got 'I can't remember; I can't recollect; I'm sure I would have; I think I did; I think I didn't; I don't see how I would have' etcetera, etcetera."

Mr Hide accused the Prime Minister of breaching the Cabinet manual on non-disclosure of pending proposals by discussing official reports on the incident with reporters.

Her response to many questions yesterday was that it was a matter of judgment how she used information available to her.

Meanwhile, the Doones' lawyer, John Upton QC, issued a statement last night saying he could "categorically state that neither I nor my legal team are feeding anyone questions to put to the Prime Minister".

He also said neither he nor his legal team had shown or copied the briefs of evidence to anyone.

He had been instructed by the Doones to state that they, too, had not shown or copied the documents to anyone.