The National Party says voters in regions other than Auckland will be surprised to hear they too could be subject to a fuel tax of up to 10c a litre.

Photo: RNZ / Alexander Robertson

Legislation introduced this week would allow a tax to be imposed anywhere in the country if a regional council makes the case.

From the 1 July Aucklanders will pay up to 10c extra on petrol and diesel.

National's transport spokesperson Jami-Lee Ross said Labour campaigned on a fuel tax for Auckland - nowhere else.

The "big surprise", he said, was that a regional fuel tax would be possible around the country.

"The government needs to be upfront with the rest of New Zealand and tell them that in just a few short years they're going to be seeing fuel tax in their regions as well.

"It's another opportunity for the Labour government to tax motorists more."

But the Transport Minister is assuring motorists no-one outside of Auckland will be hit with a regional fuel tax this term of government.

The legislation prevented regional councils outside of Auckland from seeking a fuel tax until 2021, Phil Twyford said.

"In the future councils may want to take part of it but we've been clear publicly and directly to councils that this government will not be considering any other proposals for fuel taxes, other than Auckland's, in our first term of government."

Mr Twyford said he had already personally given that message to the mayors of Christchurch and Hamilton.

In its election tax policy Labour specifically talks about a tax only for Auckland, and said Labour had "no plans for any other regional fuel taxes".

Ministry of Transport officials prepared a briefing about the impact and possible risks of the tax.

They too seem to have been taken by surprise by the broad scope of the legislation.

"At the time of the impact analysis it was indicated that Auckland would be the only region to receive authorisation for the tax.

"Therefore, the cost benefit and impact analysis in this document uses Auckland as an example to show the impact of a regional fuel tax."

The document said Auckland was a highly congested city, with time spent on the roads having doubled in three years.

"Auckland's commuters are spending an extra 45 minutes a day - or four working weeks a year - stuck in traffic."

It concluded extra money from the fuel tax was needed to raise money to fix Auckland's traffic woes.

The briefing said Wellington and Hamilton had already expressed an interest in "alternative funding arrangements" to progress local transport projects.

But it noted the Automobile Association wanted a "firm commitment" the tax would not be allowed outside of Auckland.

"The AA believe other parts of the country do not face infrastructure pressures as critical as those of Auckland, and are not set to create the same burden for taxpayers on a national scale."

Last month RNZ requested all of the advice the minister Phil Twyford had received on the regional fuel tax.

Three briefing papers were identified, including a draft Cabinet paper.

Mr Twyford refused to release them on the grounds the drafting of the legislation was "still under active consideration with decisions yet to be made" - the day before the final bill was introduced to Parliament.

The government wants to shorten the public consultation process for the select committee considering the bill so the tax can be in place in Auckland in time.

The National Party said restricting legislative scrutiny was becoming a habit under this government, and this legislation - effecting Auckland and potentially the rest of the country - was too important not to have full consideration.