Pansy Wong's resignation from Parliament today is a "cynical political attempt at a cover up" over misuse of her travel perk, Labour Leader Phil Goff claims.

Mrs Wong this morning announced she was stepping down as an MP, saying the row over her use of the Parliamentary perk had been an unfair distraction to the Government and she wanted to concentrate on her family.

The Labour Party has been calling for the Auditor-General to investigate Mrs Wong's use of the perk after a Parliamentary Services inquiry cleared her of any serious misuse.

The report by former public servant Hugh McPhail found Mrs Wong and her husband breached perk rules just once by conducting private business during a trip to China in 2008. Mrs Wong apologised and paid back the $474 rebate for the China trip.

But Mr Goff today accused Mrs Wong of resigning from Parliament to attempt further investigation into her "rorting of taxpayer's money and to protect her leader John Key".

"John Key and Pansy Wong are treating the public with complete contempt if they think people are going to swallow their claim today that she's leaving to avoid becoming a 'distraction', he said.

"Pansy Wong has rushed to resign before the full extent of her wrongdoing is exposed."

Mr Goff described Mr McPhail's report as a "whitewash" and said the Auditor-General should still investigate Mrs Wong.

Auditor-General Lyn Provost said last week that she was looking into the matter but had yet to decide if an inquiry was needed.

Mr Goff accused Prime Minister John Key of using a "cynical brand of politics" in refusing to take action against Mrs Wong.

"The Prime Minister has defended Pansy Wong to the hilt throughout this scandal," he said.

"Pansy Wong has gone before Christmas so that John Key can avoid answering questions about her rort. But no-one will be fooled by his cynical brand of politics."

However, Mr Key denied Mrs Wong was pushed, saying he was very disappointed to receive her resignation.

"I think it's a regrettable decision she's been an honest and hardworking Member of Parliament but at the end of the day she's decided that the toll on her family is too great."

Mr Key said he would have been "more than comfortable" for Mrs Wong to stay on.

"There's no new information that I have to hand, nothing to suggest that the report undertaken by Mr McPhail was incorrect."

Mr Key said on learning of her decision on Friday he "kicked the tires" with her to check she really wanted to go and she took the weekend to think it over.

"The fact that she had decided she was't going to return after the 2011 election meant it was probably better to go now."

Mrs Wong said she was not leaned on to resign.

"This is a decision I've made alone, with my family."

She said that after 14 years in Parliament, it was the right time to step down and she would now concentrate of "personal and family" time.

She said her parliamentary career had put too many constraints on her husband's pursuits.

"I've decided that this will no longer be the case."

Mrs Wong said the allegations against her of improper taxpayer-funded travel was an unfair distraction to the Government

"I strongly refute those allegations and do not want to tie up the Government's and my time continuing to do so," she said.

"I want to ensure the National-led Government can progress its agenda without unnecessary distractions."

Mrs Wong said her resignation would be effective from January 17, though her salary would stop before Christmas.

She said the past few weeks had given her time to reflect on her career.

"[It has given me the chance for] the first time in 14 years I have time to reflect on my future and I've decided that my family have paid a huge price because of my all consuming political pursuits, and the National Government should not be distracted."

Mrs Wong said she hoped to deliver her valedictory speech in Parliament this afternoon.

Botany byelection

Mrs Wong said she considered waiting to resign closer to the election, but the people of Botany deserved to an MP who could give 100 per cent to those people without the distractions of the allegations.

She said some of the response in her electorate had been supportive, and some had been critical but the decision to resign was a relief.

"I'm making the right decision for the electorate of Botany."

Party whips Chris Tremain and Jo Goodhew supported Mrs Wong at her press conference this morning.

Mr Key said a byelection for Mrs Wong's Botany seat would be held on March 5.

The last day for candidate nominations to be received will be February 8, he said.

Auckland local body activist Penny Bright said she would be contesting the byelection on an anti-corruption platform for government.

The Herald understands that former Auckland City councillor and National Party Epsom electorate chairman Aaron Bhatnagar also intends to put his name forward for the nomination.

The 34-year-old Remuera resident worked as a strategist for John Banks during his unsuccessful tilt at the Super City mayoralty.

Auckland councillor Jami-Lee Ross, who represents the Howick ward in the Super City and has been touted as a possible candidate, said he would be making an announcement before the end of the year, "but I'm not in a position to comment at this stage".

Chief electoral officer Robert Peden said people in Botany needed to be clear there would be no party vote as only the local MP was being elected.

Advance voting and voting from overseas will start on February 16.

He urged Botany residents to enrol early so they could get an EasyVote card which made voting easier.

A general election will be held later next year.

- With NZHERALD STAFF and NZPA