Metiria Turei. Photo / Mark Mitchell

Metiria Turei. Photo / Mark Mitchell

The Green Party has promised to throw open its MPs' expenses each year - and Act and the Maori Party are considering that too, a move which will put pressure on the big parties to follow suit.

Metiria Turei used her first speech as Greens co-leader yesterday to lay down the challenge at the party's annual conference in Dunedin.

She said all MPs would release their spending on air travel, taxis, rental car hire, Wellington accommodation and hotel costs.

"It's traditionally the role of the Green Party to keep the old grey parties honest, and we will do so again," she said.

The Greens' decision followed agreement by co-leader Russel Norman and fellow Mt Albert candidate Act MP John Boscawen to release their spending to the Herald on Sunday.

The two major parties are so far resisting any changes - but yesterday Maori Party co-leader Tariana Turia said she had no objections to parliamentary expenses being public and would discuss it with her caucus.

"If the public were asking for us to be transparent, I'm happy to be transparent.

"I'm certainly not opposed to members of the party being transparent at all.

"It is public money and I'm more than happy to provide them with that information."

Act leader Rodney Hide has also told the Herald on Sunday he will provide his own expenses and talk to his MPs about following suit, although it was unclear whether this might be a regular disclosure.

The moves follow weeks of furore in Britain after expenses claimed by House of Commons MPs were made public, including claims for moat cleaning, duck houses and mortgages that were already paid off.

In New Zealand, Parliamentary Services is exempt from the Official Information Act and the Speaker and leaders of the major parties have so far resisted any calls for MPs to reveal their expenses, saying the system is already robust and more constrained than in Britain.

But the Green Party's breaking ranks - especially if Act and the Maori Party follow - will heighten the pressure.

Yesterday, Labour leader Phil Goff referred questions to the party's whip, Darren Hughes. A spokeswoman said he believed the current system had enough checks and balances in place and Labour did not intend to change at this stage.

Prime Minister John Key was unavailable for comment yesterday but has earlier said the Speaker did not believe change was necessary and any moves were a matter for party leaders and Parliament itself to consider.