Wellington, Aug 12 NZPA - A group representing former MPs says it will fight to retain travel discounts.

Details of MPs' expense claims were released for the first time last month.

Present and former MPs elected before 1999 receive a 60 percent discount on travel after nine years of service; after 12 years they get 75 percent and after 15 years they get 90 percent off.

Former prime ministers also get annuity payments of about $40,000 a year and surviving spouses can get about $20,000.

Association of Former Members of Parliament president Graham Kelly said the allowances were part of legally binding terms of employment.

"Our conditions were set at the time for those members -- there are not that many involved -- and it's a contract between the Government and them which would be broken if it was changed without mutual agreement," the former Labour MP told the New Zealand Herald.

The allowance was taken into account when salary rates were set, he said.

Former National Cabinet member Ian Shearer said MPs were less supported in the past and had good reasons for receiving allowances.

"There were a lot less of the fringe benefits available in those days so all of this has to be taken into account in this package.

"The wife and the family were involved in it...it is a heck of a lot easier now."

Meanwhile, Maori Party MP Hone Harawira said he would try to cut back on travel costs over his large electorate by hitchhiking.

Prime Minister John Key said has ordered a review, due to report by the end of the month, would deal with housing allowances and possibly other areas of MPs expenses.