Key Points:

Former National leader Don Brash says he cannot remember a May 2005 email with an attachment spelling out the Exclusive Brethren's plans for an election flyer campaign, despite new evidence suggesting he received it.

Dr Brash has previously denied ever receiving or seeing the May 24 email sent by Brethren member Ron Hickmott, outlining church members' plans for a $1 million campaign aimed at building "trust" in National and "mistrust" in the Government.

Dr Brash has repeatedly said the first he knew of the Brethren's pamphlet campaign was in August last year.

The May 24 email was revealed in Nicky Hager's book The Hollow Men, but Dr Brash has since said it was either "fiction" or it went to an indirect email address and was cleared by staff.

However, Hager today released emails, not printed in the book, suggesting otherwise.

They appear to show the original email - marked high importance and referring to the attached letter - went to Dr Brash's "" email address.

It was apparently cleared by Dr Brash's aide Bryan Sinclair, who forwarded it to the leader with the comment: "From the Brethren. I usually avoid tangling you up with this, but this is worth reading as it looks like $$ are involved here".

The documents show Dr Brash replying later that day.

"Thanks Bryan. Yes our friends from the Brethren bailed me up at breakfast this morning. I have forwarded this for reaction from Steven (Joyce, National's campaign manager). Don".

The documents show Mr Hickmott sent his email at 2.15pm. It was forwarded to Dr Brash's work email at 4.13pm by Mr Sinclair and Dr Brash acknowledged receiving it at 6.49pm.

But Dr Brash today said he had no memory of the email, which led him to believe he had never opened the attached letter.

Dr Brash said through a spokesman that if he had read it he was sure he would remember it, "given the big dollars involved".

However, Dr Brash said he was still not ruling out the possibility the emails were forged.

But Hager today said the emails showed Dr Brash's main claim about the book's "lies and inaccuracies" were not true.

He said he had kept back the last details of the emails to see whether Dr Brash would come clean once he had read the book or whether he would try to deny it, based on the lack of explicit evidence in the book.

"What the whole book is about is how politicians assess what is known and then try and wriggle their way or untruth their way out of it," he told NZPA.

"So I left one thing and that's exactly what happened.

"It's basically the final example of what I was talking about so I didn't just leave the book sitting there for them to try and deceive their way out of it. I saved the last piece of stuff."