A major security lapse within the Labour Party appears to have exposed top secret political information and personal financial details.

The information has fallen into the hands of Cameron Slater, who publishes the Whale Oil blog.

Slater said he had emails, financial details, party planning information and membership data.

"Nothing illegal was done to access the information. The information is freely available to anybody who knows where to look."

Slater supplied the Herald on Sunday with a sample of the information he has obtained.

The proof was a copy of the minutes of a "Labour North" meeting held on May 25 this year, serving the party's candidates for the five electorates north of the Auckland Harbour Bridge.

The minute stated the "Labour North" collective should "use Parliamentary Services for best outcome of LP (Labour Party)".

Parliamentary Services rules strictly forbid the use of services for campaigning purposes.

Slater said the document proved the Labour Party was using taxpayer money to run its own business.

The minutes also listed the presence of Australian Labor Party activist Sandy Rippingale. She was a senior figure of 30 years with the party.

Slater said the visit by Rippingale to the "Labour North" meeting showed the party was subject to foreign influence.

Rippingale told the Herald on Sunday she was in New Zealand to attend the Labour Party congress.

Asked if she was working on the election campaign, Rippingale said: "I can't make comment on the relationship between the two Labour (Labor) parties."

Labour MP Darien Fenton denied the party used Parliamentary Services to fund campaign or party business.

She said minutes of meetings were taken by volunteers and could contain errors.

However, she conceded that there had been pressure to use the Parliamentary staff member for party business.

"It has been an area of tension. It is an ongoing discussion with them about how we protect the role of the staff member and the MP.

"I've said they can't use the office for a whole range of things. I'm really confident I've done nothing wrong."

Fenton was concerned by the leak of information. "I have no idea how he would have got that information."

Labour Party president Moira Coatsworth said she could not discuss the issue until she had spoken to party secretary Chris Flatt, then later refused to comment.

Political scientist Bryce Edward said the information could be a fascinating insight into how Labour worked.

He said information of membership would be concerning to those who had entrusted personal information to the party.