Labour leader Phil Goff today called for Botany MP' Pansy Wong's breach of international travel rebate rules to be referred to the Auditor-General.

Mrs Wong was today cleared of any serious misuse of her Parliamentary travel allowance after admitting misusing the perk during a trip to China with her husband.

The National MP says she did not realise she had breached the rules at the time but resigned from her Women's Affairs and ethnic affairs portfolios last month when it was revealed that she and Mr Wong had done business while using the taxpayer-funded travel discount in China.

Under the rules of use, the discount - 90 per cent for Mrs and Mr Wong - is on airfares for private travel only and not to be used for business - though MPs are now allowed to use it for travel-related to their parliamentary work.

The investigation looked into 13 international trips made by Mrs Wong and her husband together or separately since 2000 and found that one trip, a flight from Beijing to Lianyungang, China in December 2008, could have been in breach of the Speaker's Directions.

"While this trip was unplanned and inadvertent, it could be construed as having been for a private business purpose," the report said, and former senior public servant Hugh McPhail, who conducted the report, recommended Mrs Wong and her husband repay the travel rebate for that trip of $237.06 each.

"The report simply swallows the story as told by the Wongs, who have already been caught rorting taxpayers' money," Mr Goff said today.

"How can their word be trusted? This is a once-over-lightly investigation that has barely scratched the surface. It certainly does not tell us what the Wongs have been up to."

Mr Goff said the report revealed the Wongs had taken 13 overseas trips and claimed $54,149 on the travel rebate.

"Five of those were taken by Sammy Wong alone... the same report reveals that Sammy Wong has business interests in China and Vietnam - the very countries he travelled to on these so-called holidays at the taxpayers' expense.''

Mr Goff said the report also revealed Sammy Wong had claimed nearly $93,935 in domestic travel subsidies, which MPs' spouses are entitled to and are not permitted to be used for business purposes.

"He advised the author (of the report) that those trips were not for private business purposes or that he has 'no recollection' of any business purpose," Mr Goff said.

"His word is again simply accepted, despite the fact that many of the trips were to Christchurch where he has significant business interests."

Wong considered quitting Parliament

Earlier, Mrs Wong considered resigning from Parliament after admitting misusing the Parliamentary travel perk.

The investigation, conducted on behalf of Parliamentary Service by former senior public servant Hugh McPhail, found "no evidence of systemic abuse" of the travel allowance by either Mrs Wong or her husband Sammy.

Mrs Wong, who accepted the report's findings, apologised and said she would repay the money, told reporters the trip to Lianyungang was a side trip during a visit to China. The purpose of the China visit was a holiday and to meet with "Little Pumpkin", the girl abandoned by her father at Melbourne railway station who now lives with her grandmother in China.

She said it did not occur to her that her witnessing of the signing of business document by her husband "could be construed as personal business... It really did not dawn on until this inquiry process".

She would have repaid the travel rebate for that portion of the trip immediately, had she realised.

As the inquiry was initiated, Mrs Wong said she considered resigning from Parliament altogether, which would trigger a byelection in her Botany electorate.

"I thought that at the time I would not want my behaviour to become a distraction for the Prime Minister and the Government.

"I was frustrated with myself because the political climate is such that New Zealanders are very fd up with the parliamentary travel subsidy. The Prime Minister has set high standards and I always want to live by them and I let myself down."

Mrs Wong said she and Sammy had been through "a pretty gruelling and thorough investigation".

While she hoped to return to Cabinet, she had no expectation that would happen immediately and "it has to be earned".

Mr McPhail's report also examined the Wongs' use of the domestic air travel entitlement and their use of an electorate office at 735 Chapel Road, Botany, Auckland, as a registered office for a commercial business purpose. It found no evidence of non-compliance with the rules around either.

Labour MP Pete Hodgson started the scrutiny on Mrs Wong's travel when he questioned her in Parliament as to whether she should have signed her occupation as a Government Minister, instead of Member of Parliament, when witnessing a business deal of her husband's in China.