New Nicky Hager book won't be about Labour - Little

Labour leader Andrew Little says he's not worried in the slightest about the impending release of another book by investigative author Nicky Hager.

The new book will be unveiled on Tuesday at Unity Books in Wellington, with Hager saying it's not a sequel to Dirty Politics.

Unity staff told Newshub they had no idea what it was about either, and wouldn't until the boxes were opened on Tuesday afternoon. 

Mr Little is sure it won't be about his party.

"I can't imagine, I don't think so, I don't expect so. But then, we're very clean. I guess we'll just have to wait and see."

Dirty Politics took aim at the National Party, but it didn't do Labour any good - the party falling to its worst result in decades.

Mr Little says Mr Hager's past books have contributed to the democratic process, and he's looking forward to seeing what he has in store this time.

"We're still six months out from the election. If you've got an important issue to write about and a point to make, good on him."

There has been speculation on left-wing blogs the book could be about former Prime Minister John Key, and reveal unheard reasons behind his shock resignation last year, or the Panama Papers tax scandal, which Hager worked on.

Talking to pop culture news site The Spinoff in 2015, Hager said he was working on "one of the most important projects that I could imagine in my life", but it's not clear if this book is that project come to fruition. 

A post on the Whale Oil blog, which featured heavily in Dirty Politics, claims it "is extremely likely that once again his book will be based on private information stolen in a politically motivated criminal hack".

The book's release date is close to six months exactly before the election. Dirty Politics came out just over a month before the 2014 election.