Investigative journalist Nicky Hager is keeping the title and topic of his new book under wraps until its launch this week.

The book will be released in Wellington on Tuesday night.

A book launch invite gives the only detail about what can be expected from the author.

"The book is not a sequel to Dirty Politics nor related to the election," the flyer says.

"It is a completely different book but nonetheless gripping and important."

The book comes three years after the release of Dirty Politics in 2014, shortly before the last election.

That book was based on internal communications between right wing WhaleOil blogger Cameron Slater and a network of National Party figures.

The information was given to Mr Hager by an anonymous hacker.

Last month Mr Hager filed a human rights claim against Westpac over a decision to give police his account details, without asking for a warrant, as part of a police investigation to identify the hacker.

In December a court found a 10-hour search of Mr Hager's Wellington home in October 2014 was illegal because police had not told the court they were conducting a "media search" when they applied for a warrant.

A separate claim against the police is currently before the High Court.