Prime Minister Jacinda Ardern has suggested she has had a "hint" of what economic growth figures due out this week will show and she is "pretty pleased".

The Prime Minister's office is insisting she has not had advance notice of official statistics, after she said in an interview that she was "pleased" by what economic growth figures will show on Thursday.

In an interview with NewstalkZB, Ardern was asked about gross domestic product numbers due out this week, and whether she had seen them.

"I get a hint, yes," Ardern said.

Host Mike Hosking asked if the numbers were good.

READ MORE: NZ economy may not be as slow as business confidence suggests - for now

"I'm pretty pleased," Ardern said.

Ardern's office swiftly denied she had seen the figures, which are meant to be under strict embargo until 10:45am on Thursday when they are released by Statistics New Zealand.

BRADEN FASTIER/STUFF National leader Simon Bridges said the question put to Ardern was clear, and the Prime Minister appeared to be "distracted" by the troubles of the coalition.

"The Prime Minister made a mistake," a spokesman said.

"She has not seen, because we do not receive, the GDP numbers."

The spokesman said she "wasn't giving any indication" of what the figures would show. Instead, she was referring to unaudited financial results of the New Zealand Government, otherwise known as the Crown accounts.

Hosking clearly asked Ardern about "the GDP numbers".

National leader Simon Bridges said Ardern appeared to have been distracted by the troubles of the coalition, saying he had listened to the interview live.

"I heard, quite clearly, as question on GDP [gross domestic product] from Mike Hosking," Bridges told reporters, before National's weekly caucus meeting.

"I know what he was asking, I think most listeners would know what he was asking, and the reality is, she mistook what he was saying."

Bridges said it appeared the comments had an impact on the New Zealand dollar.

"She needs to get that right, that she didn't shows that she is distracted, she's focused on the shambles of the coalition, rather than what matters to New Zealand."

Asked if he was suggesting Ardern did not know the difference between the Crown accounts and GDP figures, Bridges said: "Well, in truth I think that is a question for her. She was asked a question about GDP figures, not about Crown accounts."

A Treasury official confirmed the next release of the Crown accounts, for the 12 months to June 30, would be released in October.

Speaking to reporters, Ardern maintained she was talking about the Crown accounts, but acknowledged that was not clear to listeners and that Hosking was talking about something different.

Asked about the New Zealand dollar increasing after the comments, Ardern said it "absolutely should not be the case".

"Of course the Prime Minister does not get the GDP figures. Nor should they. Those are held by Statistics [New Zealand]. I could not comment on those because I had not seen them."

The speed with which Ardern's office acknowledged the error reflects how important it is to maintain confidence that market sensitive information handled carefully.

Any time figures on GDP are released they are likely to influence both currency markets and products linked to interest rates. This week's release is even more closely watched than usual, with the outcome likely to see markets guessing whether they will see the Reserve Bank cut interest rates in the coming weeks.

Statistics New Zealand has reacted to the story, with Government Statistician Liz MacPherson adamant there are "absolutely not" any hints to anyone, including the Prime Minister, before the release of economic growth figures.

"Stats NZ has strict embargo rules about tier one statistics such as gross domestic product. These figures are market sensitive and are never given to anyone in advance of the release day," MacPherson said.

"There is a short formal briefing for relevant government ministers in the hour before the release time of 10.45am on the day, but that is under strict embargo lock-up conditions," Ms MacPherson says. "Even then ministers are not allowed to communicate the information to anyone else before 10.45am".

Economists are expecting the figures will show the economy picked up slightly in the three months to June 30, and may have expanded by up to 0.9 per cent in the quarter.

However if the economy grew by less than forecast, say 0.6 per cent or lower, annual growth will have fallen to around 2.5 per cent, the level at which governor Adrian Orr suggested he would consider cutting the official cash rate to all time lows.