A former contract worker for National Party Tauranga candidate Bob Clarkson has made new allegations against him.

Vivienne d'Or, 53, made her claim of a sexual advance as the battle for New Zealand First leader Winston Peters' electorate seat became the most bitter of the campaign.

Mr Clarkson refused media interviews after Ms d'Or went public, but in a short statement denied "all the allegations" and said he was taking legal action.

Mr Peters, who has been trailing in the polls, was panicking about the prospect of losing his seat and was stooping to gutter politics, Mr Clarkson said.

"That isn't how we do things in Tauranga and Mr Peters will soon learn that," he said.

Mr Clarkson yesterday said he sacked Ms d'Or in 2002 for swearing, and that she had then made spurious claims of sexual harassment.

Ms d'Or returned from a holiday in Australia today, saying she was "gobsmacked" to find herself the centre of media attention.

Mr Peters raised the sexual harassment incident yesterday in a speech in Tauranga.

It escalated into the nasty row that was played out today.

The company Ms d'Or, a single divorcee, was employed by Mr Clarkson to sell advertising and corporate boxes for Baypark Stadium in 2001.

"Right at the very start I had problems with him... sexual harassment type problems," Ms d'Or told reporters at Auckland Airport.

"One of the things he asked me to do was to go back to his house for a meeting by myself because his wife was away looking after her dying sister.

"I told him to piss off. He then said it was a joke."

After that Mr Clarkson had continually referred to "betting his left testicle" and she had asked him to stop.

"He just got worse and worse... at one meeting he was busy telling us about his sex life," she said.

Mr Clarkson had sacked her and she had used a lawyer to get $65,000 for unpaid commission and to discuss his behaviour towards her.

"All I wanted was my money and to move away from him," she said.

Her story had been brought to Mr Peters' attention and he contacted her, she said.

She said Mr Peters offered no inducements of any kind. Her flight back to New Zealand had simply been a return from holiday.

Ms d'Or said she did not believe Mr Clarkson was fit to be an MP, but it was up to Tauranga voters to decide that. "I am going to vote for Labour," she added.

National Party leader Don Brash said the party was standing behind Mr Clarkson.