In the heat of the by-election battle for Mt Albert, two MPs are taking the surprise step of breaking ranks with all their political colleagues to disclose their Parliamentary expenses.

Green Party co-leader Russel Norman and Act's John Boscawen have fronted up to answer a series of questions disclosing their Parliamentary expenses - questions that all 121 MPs refused to answer last week. No other issue has, until now, inspired such unity across the different Parliamentary factions as protecting the secrecy around their expenses.

In Britain, a similar "conspiracy of silence" has dramatically disintegrated with the leaking of MPs' expenses rorts, costing the Westminster Speaker and at least a dozen other MPs their jobs.

It began when one MP voluntarily disclosed his expenses spending to London's Sunday Times last year, putting pressure on others to do the same.

Here, National's Mt Albert by-election candidate Melissa Lee has refused to reveal what she spends her $14,800 annual expenses top-up on, and how much she claims for accommodation in Wellington, and on taxis, rental cars and airfares.

If she was to disclose her expenses, it would put pressure on other National MPs to do the same.

Lee told the Herald on Sunday on Wednesday that she was "very happy to answer your questions" but, by Friday, after talking to National's Parliamentary whip Nathan Guy, she changed her tune and was "too busy".

Lee had already been accused of using public funding for her company, Asia Vision, to produce a National Party promotional video for last year's general election. NZ on Air investigated the use of the $1.2 million, and this month cleared her of any wrongdoing.

The publication of the MPs' register of interests this week revealed that as well as Asia Vision, Lee also has directorship and, in most cases, a controlling interest in a talent agency, two other production companies that are not currently trading, and three inactive martial arts companies.

Yesterday afternoon, Lee issued a statement saying details of the properties she owned and her superannuation scheme were available through the MPs' register.

"I live in Auckland, in a house I own. This is my primary residence. I don't have a partner," she said. "There are Parliamentary rules around MP travel and accommodation claims, which I comply with ... I have been careful to separate parliamentary and campaign expenses."

Last week the Herald on Sunday reported that MPs are paid $1.8 million for Parliamentary expenses, including entertainment and gifts. The newspaper asked each of them to account for the money - but no one did so.

But this week, coinciding with Norman and Boscawen's disclosures, the other Green MPs have agreed to disclose their expenses.

Act Party leader Rodney Hide has promised to disclose his expenses and is expected to talk to the other three Act MPs about doing the same.

In releasing his expenses, Boscawen said, "There's no hidden stuff here. I am not ripping off the taxpayer."

MPs are not required to keep any record of how they spend the annual $14,800 top-up. They are also entitled to claim back costs of taxis, rental cars, driving their own cars, domestic air travel and up to 90 per cent of the cost of overseas travel. MPs from outside Wellington can also claim up to $24,000 on the costs of hotels, rental accommodation or a mortgage in the capital.

Despite a recommendation in 1999, the system is exempt from the Official Information Act, at the insistence of MPs.

Labour's Mt Albert candidate David Shearer has no Parliamentary expenses to declare, as he is not yet an MP, but he nonetheless called for greater openness around MPs' expenses.

"I absolutely support transparency," he said.

If he wins the by-election as many expect, the Herald on Sunday will seek to hold him to that commitment to transparency around expenses.

National and Labour have fought hardest over many years to keep politicians' expenses secret.

One after the other, Labour MPs have promised that their senior Parliamentary whip, Darren Hughes, will answer the questions about their expenses. Yet he refused to do so.

National's senior whip, Nathan Guy, said yesterday that answering the questions would be time-consuming but that he would ask Lee to do so.

* How they spent your money

Russel Norman

The Green Party co-leader Russel Norman pays $340 a week to rent a house in the Wellington suburb of Hataitai. He lives there with his partner Katya Paquin, who is also employed full-time by the Greens in Parliament.

Because Wellington is home, he is not entitled to claim expenses of up to $24,000 for accommodation in the capital. Paquin sometimes accompanies Norman on out-of-town trips. Norman says the two ran up $15,828 in publicly-funded air travel in the first four months of this year. Norman also spent $3794 on taxis and hire cars, but emphasised that he had not been claiming any taxi and accommodation expenses in the Mt Albert campaign.

"When in Wellington, I generally catch the bus to work at Parliament. I often get a taxi home when the buses have stopped," he says. Norman says his travel expenses may be higher than many other MPs, because as co-leader of the Greens he is required to attend events and meetings around the country.

He would also have spent sums of more than $500 on some office equipment, he said, but none on alcohol.

John Boscawen

The Auckland-based MP pays $160 a night to stay in the Bolton St Hotel, three minutes' walk from Parliament.

He ran up $3500 in hotel expenses in the first five months after the election. he expects to claim up to $6000 on Wellington accommodation expenses this financial year, which ends next month.

Boscawen estimated his domestic air travel will have cost the taxpayer up to $13,000. That included regular travel between Auckland and Wellington, and two trips to Christchurch.

He was also claiming for two return trips to Wellington made by his partner Jane, one for the opening of Parliament and the other for his maiden speech. "She is entitled to have travelled far more frequently, but works five days a week," he says.

Boscawen also flew business class to Vietnam and Japan last month as a member of the Speaker's Tour, at an estimated public cost of $10,000.

Act MPs are opening an Auckland office, but Boscawen did not know how many items costing more than $500 he would buy. As for alcohol bought for Parliamentary business? "I do not drink alcohol," he says.