National leader John Key is continuing to refuse disclosing which consultants his party hires, saying a "vindictive" Labour Government would deny them business.

He has also ruled out someone within the party being to blame for leaks and is resting the blame on Parliamentary Services.

At the weekend investigative author Nicky Hager reported Mr Key had hired Australian political strategy company Crosby/Textor.

The company had courted controversy for tactics including push polling, designed to influence voters.

Hager's report included diary type references and dates and details of Mr Key's meetings.

Yesterday Mr Key raised the issue with Parliamentary Services.

Hager wrote The Hollow Men based on 475 stolen or leaked emails from former leader Don Brash which led to him leaving Parliament. A police investigation found no evidence of hacking and Hager has always maintained the emails were leaked to him by National Party sources and said those who claimed they were gained by theft should apologise to him.

Mr Key said he was not "overly worried" about potential future releases of party information.

But "any company's email system that is exposed to the public can be portrayed in a way that is deemed to be negative," he told Breakfast on TV One.

"We deserve to have confidentiality only because I think every organisation deserves that and unfortunately Parliamentary Services can't give us that."

He did not believe anyone in National would assist Hager. "No. I don't accept that, no."

Mr Key continued to refuse to state whether National used Crosby/Textor. He said a "vindictive" Labour Government would stop using any consultants that National also hired.

"We're not denying we use consultants for focus groups and we're not denying we use consultants for polling," he said.

"We won't be asking our consultants to do things that clearly Labour are. We have ruled out push polling, Labour have not."

Asked "what advice are your advisers giving on not talking about your advisers?" Mr Key said: "I haven't sought advice on that."

Deputy leader Bill English tried to turn the focus on to Labour.

"Labour is obsessed with who gives advice to National. The public I would have to say is much more concerned with an economy that's turning down interest rates that are still too high and law and order that's out of control," he said on National Radio.

Prime Minister Helen Clark yesterday said she was happy to name the consultants Labour used -- UMR for polling, Brian Edwards for media training and whoever ended up helping with the election advertising campaign.

To the best of her knowledge Labour did not hire political strategists and this was all done within the party.

"I am the chief political strategist."

She said push polling was wrong.