National leader Simon Bridges has stopped short of pointing the finger at the Government for leaking details of his travel expenses to the media - but says they are looking for distractions from their own problems.

Speaking to reporters this morning, Bridges said he didn't know who leaked his quarterly expenses, which show he racked up more than $100,000 in accommodation and travel.

"I don't know, I think you' ve got to say the Government is looking for every distraction they can rather than focusing on the things they should be – plummeting business confidence, economy in downturn, strikes."

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He wouldn't say outright whether he thought any Government MP had leaked the information, which is due to be publicly released later this week.

"It isn't National, I'm very confident about that."

Newshub reported last night that MPs' expenses for travel and accommodation, which it had been leaked, showed Bridges' bill for the last three months came to $113,973. Most of that, $83,693, was spent on crown limousines.

Bridges welcomed an inquiry by Speaker Trevor Mallard, who has said he is seeking a list of all those who had access to the expenses ahead of their release, and also why Bridges' and his own expenses seemed high.

"It's good to see Trevor Mallard's doing an inquiry and we'll see what happens," Bridges said.

He confirmed all National MPs were among those who had access to the expenses.

National MP Nick Smith said there was no evidence it had been leaked from somebody within the party and said it was more likely that someone was having a "pretty cheap shot" at Bridges.

"Sixty-six public meetings - I have never seen any minister or leader of the opposition work that hard", Smith said of Bridges' regional roadshow.


"So I just say full credit to Simon for getting out and meeting with New Zealanders, it will make him a better leader of the opposition."

Prime Minister Jacinda Ardern has denied any of her MPs were behind the leak.

"We've sought assurances from Ministerial Services, who manage this information, that none of the opposition's numbers were shared with anyone but them and they've given us that assurance."

Ardern said she could categorically rule out anyone in Labour having access to the information, including the whips.

"The only groups, as I understand, who will have had access are the opposition themselves and the Speaker," she told reporters.

Ardern said there was no need to seek any assurance from Mallard.

"He is impartial. He doesn't attend caucus, he presides as an officer of Parliament. It's a really serious allegation to suggest that he could have been involved in some way."

Earlier, Ardern said that when she saw her expenses after first becoming party leader, she was surprised how high the figure for surface travel was.

"I remember wanting to change my behaviour as a result of that. These numbers, sometimes, when you think you're just out doing your job you suddenly receive an expense and some of the figures can be extraordinary. It certainly threw me the first time that happened," she told Newstalk ZB.

Ardern's surface travel for the first quarter, which included her time as opposition leader, totalled $82,795.