Prime Minister Jacinda Ardern far outspent her Cabinet colleagues over the past three months, racking up more than $175,000 in travel and accommodation expenses, mostly overseas.

The latest ministerial expenses - tracking July to September - show Ardern spent $40,483 within New Zealand and another $136,922 on international travel.

The time period covers several major trips including the Pacific Islands Forum in Tuvalu and the United Nations General Assembly in New York.

Overall, ministers spent roughly $1.6 million in the last quarter. The figures do not include one-off expenses charged to ministerial credit cards.

After Ardern, the next highest spender was Agriculture Minister Damien O'Connor who spent $112,157 in total, $70,845 of which was overseas.

Over the quarter, O'Connor visited both China and Thailand to take part in negotiations over the Regional Comprehensive Economic Partnership (RCEP).

Trade Minister David Parker also had a heavy overseas schedule, visiting Spain, Ireland and the United Kingdom, spending a total of $93,382.

Looking at expenses just within New Zealand, Regional Development Minister and NZ First MP Shane Jones had the highest travel bill, spending $50,205.

Ardern has previously defended Jones' expensive travel costs as a necessary part of his job visiting the regions.

By comparison, National Party leader Simon Bridges spent $40,451 on domestic travel and accommodation over the same period.

The expenses release is the first since the Department of Internal Affairs adjusted the rates at which Crown limousines are charged out to the Opposition.

Opposition leaders have historically been charged a much higher rate than ministers to use the VIP vehicles, most recently $171 per hour compared to $68 per hour.

In a statement, Parliament Speaker Trevor Mallard today announced they had been charged at the same rate since July 1 this year.

"I am pleased to see this change take place as it will ensure consistency, increase transparency, and reduce the confusion that the different rates have created."

Mallard put the long-time difference down to "a historic bureaucratic anomaly" and acknowledged it had caused confusion.

National was thrown into turmoil last year after the early leak of Bridges' expenses and criticism of his total $113,973 bill.

By RNZ